Area 99, Rick Liddell's Texas Instruments TI99/4A site. - Rick's site has slick graphics and several essays detailing his memories of using the TI-99 and the reasons why he still loves it. Also has plenty of his favorite links and some suggestions on emulation.
The Assembly Guru - Bruce Harrison's Home Page- Descriptions and order information for his public domain software.
Getting Started With The TI-99/4A - The Book - The text of a TI99/4A Book, Getting Started With the Texas Instruments TI99/4A Home Computer (1983), a photo of a TI99/4a, some tips on programming a TI99/4a and some music composed for the TI99/4a.
Jon Guidry's TI-99 Page - Photos, hardware information, and even a guide to adding a 3.5" floppy drive to your TI-99!
Lapinkult's TI99/4A Page - On my TI Page you will find some freeware programmes I wrote in 1983-1989. There are also Highscore lists for several games, hints for TI Adventure Games, Photos of common and rare TI Parts...