Marsh, feel free to delete this & edit your post, or leave it as an addon, either way.
Note: I'm not plugging any of these vendors (well, some of them are decidedly better than their competition...) Some of these places make parts that are resold by others (for example, many APE parts can be purchased at other places).
APE - One of the places with a reasonably good selection of aftermarket go-fast toys for the FJ, including billet clutch baskets, heavy duty studs, and heavy duty head nuts. They'll also do machine work for things like big-bore kits.
Bellflower Motorsports - A dealer's site that has a parts fiche so you can figure out part numbers and names of things that you broke.
Marauder Group - Cruiser website, with an excellent guide to telling the difference between lean and rich at idle.
Factory Pro - Direct link to their section on tuning carbs in an engine, a good starting point.
Factory Pro - Selection of jet kits and various carb parts including emulsion tubes, specific to the FJ. Considered by many to be superior to Dynojet recalibration kits.
Beasley Composites - Dragbike bodywork, difficult to find for the FJ.
Rev's Performance - One of a few vendors that carry engine bars (Renntec) for the FJ.
Motorcycle Specifications - A good resource for comparing models and specs on a wide variety of two wheeled machines.
MPS - Vendor with limited FJ support, but parts such as clutch controllers and airshifters that will work for dragracing an FJ.
Cometic - Gasket supplier that can make custom thickness head/base gaskets, as well as replacement gaskets in FJ's.
MR Cycles - Another dealer page with a parts fiche.
Schnitz Racing - May be outdated; Schnitz used to make single stage lockup clutches for the FJ, but it's not listed online anymore. A must for the extremely high power guys (turbos, etc).
Dan's M/C - A quick guide to reading sparkplugs, various links to some good advice on how to work on motorcycles.
Zanotti's - A dealer with often discounted parts, better prices occasionally available elsewhere.