I'm not huge on racing stripes, but I've owned a car with 'em before (silver '87 Fireturd with black stripes), and it got a lot of looks. Depends on whether or not you want attention; me, I try to make my car as subtle as I can so that I don't have cops eyeballing me and pointing speed guns at my car all of the time.
Darn near anything will go good with black. Just don't go for some icky neon yellow, pink, or green crap, and it'll look good. Red or blue over black would be more subtle, whereas white or yellow would really stand out in contrast - what kind of effect do you desire?
Silver would be my pick, too, but that's because I've got a sort of black/gray/silver theme going on with my black notch, so it depends how the rest of yours is set up - your interior, your wheels, etc. Silver + yellow + black probably would not jive. It's hard to put anything else with a yellow-on-black scheme (except more yellow or black) without it looking weird or tacky, but it depends on how obvious or minor your other yellow details are. (Pics would really help.)
A single, big fat ol' stripe up the hood would be nice, IMHO, kinda like the mid-80's GT's; carrying stripes all the way from the front air dam all the way over the roof and down below the exhaust, however, is a tad bit overkill. Being that you've got a Stormin' Norman hood, I'd just go with stripes on the scoops back to the cowl, and that's it.
Please, please, PLEASE don't do that ridiculous single offset stripe thing that I see on every other import ricemobile out on the road. It looks like they couldn't afford the other stripe, or someone peeled it off there one night as a prank. If you're honestly using the car for autocrossing and this is a driving aid of sorts, however, do it if you absoltely must ... but you'll still look silly.
Rolls of plain ol' white vinyl for racing stripes can be had at Autozone for less than $20, IIRC. (Has a picture of a red Camaro on the front with white stripes all the way front/back.) If you wanna go the bling route, they make rolls of chrome tape, too, which are usually found right next to the white vinyl there...
If you want a first-hand visual idea of what it'll look like, or if you want to try some different striping ideas out, get some of that blue Painter's Masking Tape (or, for a more yellow look, plain ol' masking tape works, too), and lay some strips of that on there, maybe take a few pics, and then manipulate the color with Photoshop to see what'd look best.
Enjoy!