Clay Thompson is hosting the technical articles from the Waringstown TR7 site which is being taken down. He's also got several other very nice technical articles for your perusal.
Ramon Alban's collection of articles on the fuel injection of the SD1/3500, useful stuff for the Wedge fuelies, especially the TR8 but also relevant for the TR7 FI as many of the Bosch components and functions are similar
Paul Heritage's site has scans of almost every article every printed about the Wedge cars. There's lots of other good stuff there too.
William Paris' technical site which contains detailed documentation of various upgrades and modifications that William has performed to his TR8, and the results. William has performed the mysterious, often talked about but never seen, Volvo / Escort from brake conversion and has a treasure trove of documentation of this very cost effective and significant conversion.
The British Car, The Wedge Shop's forum for British cars. A great place to be if you're thinking of hot-rodding your wedge. Not just a forum however, The Wedge Shop is a TR7/TR8 parts vendor that in many cases is the only US based supplier of some Wedge parts. The forum has lots of good advice, and many TWOA members frequent this forum too!
The Triumph Experience is a great forum for all things Triumph. Part of the Autoshrine network, there are always quite a few TR7 and TR8 folks hanging out on the forum. Quite a great site to get unbiased help.
Triumph Wedge Owners Association: Formerly the TR8 Car Club of America TWOA is an affiliate Chapter of the Vintage Triumph Register