I'll second the mention of the Turtle Wax carpet and upholstery shampoo. It works quite well. I used it on my 2000 Cirrus last year to clean up some er...vomit...not mine, by the way, and it worked wonders. Even killed the smell. First time someone yaked in my car, but such are the risks when one is the DD at a party.
Anyway, this Turtle Wax stuff has OxyClean in it(you know, the over-excited dude who does the infomercials). Brought the colour back from a dull grey to a dark flint. Sorry, no pics. And the brushes on the cans are great for working all the grit that sets into your carpets and seats. If the stains are old, you might have to shampoo twice or thrice to get them out.
The stuff comes in two types: one for automotive carpets, and one for upholstery. I've used the carpet stuff on everything with no ill effects.
Hope this helps.