Well, the best gains in terms of cost effectiveness are still the basics. Shamu's list includes a lot of extreme measures that are going to cost a lot per lb saved (and no, I don't think he's done most of them).
The most cost-effective basics for dropping weight on a street machine:
1) Zero-cost stuff: Get rid of the windshield washer fluid reservoir system and its tubing/jets, get rid of the top engine plastic cover (if anything it traps heat).
2) Battery reloc + sub/spare removal. Remove heavy battery from front, remove heavy subwoofer and spare tire from rear, install light battery in trunk area. Net drop is 64lbs, 35 from the front and 29 from the rear. Cost is one Odyssey PC-680 battery, plus mounting and cabling hardware and some labor time.
DIY: Battery Relo
3) Lightweight wheels+tires. I went with 18" Forgestars and Continental DW tires. There are lots of options, but it's rotating unsprung mass and it's worth way more than gutting sprung weight on the car.
4) Exhaust system. Look into options like Fast Intentions - good gains and a nice weight drop from the factory system. If you combine it with their long-tube headers it's even more weight drop, and more of it up-front.
Once you get those basics knocked out, then start evaluating the rest. Whatever level of interior stripping you can tolerate on the street, and lighter racing buckets are both reasonable options.