A friend of mine owns an S-10 and is looking to add a lot of mods to it - I was wondering if those of you who have done this could share some websites of online stores you used to buy performance upgrades, or interior/exterior items.

It would be an excellent help to him - thanks!

I use eBay and Summit.

I personally own a Pontiac Grand Prix, and there are some websites I use that are specific (for example, owning a 3800 V6 engine) to the type of equipment on my vehicle. I was wondering if there were "truck/suv-only" website favorites that catered to the tailgate crowd.

Here is a few other places I have purchased from.
http://autoaccessories4less.com/
http://www.stylinconcepts.com/
http://lb5.netster.com/index/Site=d3d3LnNwb3J0dHJ1Y2tpbmdzdG9yZS5jb20%3D
http://www.alldiscountautoparts.com/ChevyS10.html
http://www.truckaddons.com/manufactures/saddleman.htm?source=GOTO&keyword=saddleman&OVRAW=saddleman&OVKEY=saddleman&OVMTC=standard