The following articles, books, and websites have been of indispensable assistance to me.  I am sure you'll find them informative as well. 
    
 

Baerg, William J.  The Tarantula.  Lawrence: University of Kansas Press, 1958.

Bertani, Rogerio, and Pedro Ismael da Silva Junior.  The First Mygalomorph Spider without Spermathecae:
     Sickius longibulbi, with a Revalidation of Sickius (Araneae, Theraphosidae, Ischnocolinae).
     The Journal of Arachnology 30, 2002. 519-526

Bertani, Rogerio. "Revision, cladistic analysis and zoogeography of Vitalius, Nhandu, and Proshapalopus; with
     notes on other theraphosine genera." (Araneae, Theraphosidae). Arquivos de Zoologia 36(3), 2001.
     265-356.

Octavius Picard-Cambridge .Arachnida-Araneidea. Volume I . [London : Pub. for the editors by R. H. Porter]:
     1889-1902.

Celerier ML, et al.  "Venom of an aggressive African Theraphosidae (Scodra griseipes): milking the venom, a
     study of its toxicity and its characterization."  Toxicon. 31(5): 1993.  577-90.

Chamberlin, Ralph V. "New Spiders of the Family Aviculariidae." Bulletin of the Museum of Comparative
     Zoology.   1917.  Vol. LXI, No. 3.

Charpentier, Philip. "The Genus Avicularia" Exothermae.  1992.  Vol. I, No. 1.

Charpentier, Philip.  Exothermae Magazine Number One:  A New Species of Poecilotheria.  Middelkerke:
      Exothermae Publications, 1997.

Coile, Nancy C. TRI-OLOGY. 1996. Vol. 35, No. 6.

Conniff, Richard.  "Tarantulas: Earth Tigers and Bird Spiders." National Geographic.  Pages 98-115,
      September 1996.

Dougherty, TJ, et al.  "Envenomation from a “Fringed Ornamentalâ€ÂÂ� Tarantula (Poecilotheria ornata)."
     Journal of Toxicology: Clinical Toxicology Vol. 42, no. 5.  2004. 768.

Edwards, G.B. and Kenneth L. Hibbard. "The Mexican Redrump, Brachypelma vagans
     (Araneae: Theraphosidae), an exotic tarantula established in Florida."  Fla. Dept. Agric.
     & Cons. Serv., Div. Plant Industry, Entomology Circular. 1999. 394:1-2.

Gallon, Richard C.  "Revision of the African genera Pterinochilus and Eucratoscelus (Araneae,
      Theraphosidae, Harpactirinae). Bulletin of the British Arachnological Society. 2002. 12 (5).
       201-232.

Gallon, Richard C. "Revision of the Ceratogyrus spp. formerly included in Coelogenium
     (Araneae: Theraphosidae, Harpactirinae)."  Mygalomorph.  2001.  Vol. 2, No.1.

Gertsch, Willis J. American Spiders.  New York: Van Nostrand Reinhold Company, 1949.

Hancock, Kathleen and John.  Tarantulas: Keeping and Breeding Arachnids in Captivity.
     Taunton: R & A Publishing, 1992.

Keyserling, E. Die Spinnen Amerikas. Brasilianische Spinnen. Nürnberg, 3: 1891. 1-278.

Koch, C. L. Die Arachniden. Nürnberg, Neunter Band, 1842.

Locht, A., et al. "Distribution and Natural History of Mexican Species of Brachypelma with
     Morphological Evidence for Their Synonymy." Journal of Arachnology 27, 1999.
     196-200.

Lucas, SM, et al. "Mygalomorph spider bites: a report on 91 cases in the state of Sao Paulo, Brazil."
     Toxicon. 32(10):1994. 1211-5.

Marshall, Samuel D. Tarantulas and Other Arachnids.  Hauppauge: Barron's Educational
     Series, 1996.  ISBN 0-8120-9315-1

 Nentwig, Wolfgangand Christian Wissel.  "A comparison of prey lengths among spiders."
     Oecologia 68:4. 1986.  595 - 600.

Perez-Miles, Fernando.  "Iracema cabola: New Genus and Species of a Theraphosid
     Spider from Amazonic Brazil."  Journal of Arachnology 28.   2000. 141-148.

Pérez-Miles F, Lucas S M, da Silva P, Bertani R. "Systematic revision and cladistic analysis of Theraphosinae
     (Araneae: Theraphosidae)." Mygalomorph, 1.3:  1996. 33-62.

Platnick, Norman I.  The World Spider Catalog.  New York: The American Museum of
     Natural History, 2000.  Available online here.

Pocock, Reginald.  The Fauna of British India, Including Ceylon and Burma: Arachnida.  London: Taylor
     and Francis, 1900.

Prentice, Tom. "Theraphosidae of the Mojave Desert West and North of the Colorado River (Araneae,
     Mygalomorphae, Theraphosidae)".  Journal of Arachnology 25, 1997. 137–176.

Raven, Robert J.  The Spider Infraorder Mygalomorphae (Araneae): Cladstics and Systematics.  Bulletin of The
     American Museum of Natural History, 182. 1985. 1-180.

Reichling, Steven B. and  William H. N. Gutzke.  "Phenotypic Consequences of Incubation Temperature and
     Feeding Regimen in Captive-bred Tarantulas."  Zoo Biology 17:5.  1998.  405-414.

Reichling, Steven B. The Tarantulas of Belize.  Malabar: Krieger Publishing, 2003.

Richman, D.B., B. Cutler, S. Brantley and D. Allen Dean.  Preliminary List of the Spiders of the Arid Southwest.
     New Mexico State University.  1999.

Schultz, Marguerite J. and Stanley A. The Tarantula Keeper's Guide.  Hauppage: Barron's
     Educational Series, 1998.   ISBN  0-7641-0076-9
 Here is the authors' webpage with updates on the book and personal information.

Seifert, SA.  "Sunburst Tarantula (Pterinochilus murinus) envenomation."
     Journal of Toxicology: Clinical Toxicology. Vol. 41, no. 5.  Aug 2003.  700.

Shillington, C and P. Verrell.  "Sexual strategies of a North American 'tarantula' (Araneae: Theraphosidae)."
     Ethology. Vol. 103, no. 7.  1997. 588-598

Thorell, T. Viaggio di Leonardo Fea in Birmania e regioni vicine. LXXIII. Secondo saggio sui Ragni birmani. I.
     Parallelodontes. Tubitelariae. Ann. Mus. civ. stor. nat. Genova (2) 17[=37]: 1897. 161-267.
  

Toft, Soren.  "Prey Choice and Spider Fitness."  Journal of Arachnology 27. 1999.
     301-307.
 
 

American Tarantula Society Has journal articles, books and compact discs for sale, a bulletin board, and a question/answer forum.

Arachnid World A discussion group frequented by a lot of knowledgeable and experienced people.

Arachnopets A great site by Debbie and Scott Scher with multiple discussion forums, an extensive and well-sorted selection of classified ads, a gallery, and much more.

Australian Tarantulas by Steve Nunn of Australia.  Just like the name says, it has great information on Theraphosidae in The Land Down Under.

British Tarantula Society A veritable cornucopia of information with classified ads, fantastic journal articles, surveys, a discussion board, and more.

Giant Spiders Guy Tansley's very informative site with incredible pictures.

G. Wright's Tarantula Care  G. Wright's excellent site that covers sexing, general husbandry, health, and more.

Northeast Tarantula Club A club in northeast England that is active in breeding tarantulas.

Petbugs  by Jon Fouskaris.  Has a discussion forum, bulletin board, caresheets, etc.

Phong's Tarantula Pages by Thomas Schumm. This has tarantula diaries, caresheets, breeding information, etc.

Rick C. West, Arachnologist  By Rick West of Canada.  This library of photos has become a very helpful reference for identifying tarantulas in the pet trade.

Tarantulas by Radan Kaderka.  An exceptionally informative site, particularly for those with an interest in taxonomy.

The Tarantula Store  an excellent informational resource done by Phil and Tracy of England.  It has great photos, excellent information, and an active forum.

Theraphosidae of Africa and the Middle East by Timo Raab and Ingo Wendt of Germany.  It has detailed information on the subfamily Harpactirinae.

Theraphosidae of the World and Their Care in Captivity  An outstanding site by Mikhail Bagaturov of Russia.  It contains tons of info, including detailed and up-to-date cladistic references for some species.  It's likely the most updated site on tarantulas available.  It is in both English and Russian.

Tracy's Tarantulas A site with great pictures, information, and organization by another Tracy in England.

XNism A site with caresheets and pictures from Clint in California.  He also sells tarantula calendars, the proceeds from which benefit victims of autism.