A friend of mine needs a website re-designed, but he isn't doing so well financially now... So I came up with the solution that I would just place my own adsense code on his site, with his permission, in order to be paid for building and maintaining the website. Is this against adsense TOS?
As Jerry Seinfeld used to say, "Not that there is anything wrong with that". Ha-ha. I really don't see any problem, as long as you follow all the TOS rules. It should be fine, as long as you and your friend don't have any "falling out", and the money becomes an issue. You will probably want to "lay claim" to the site in Google Webmaster Tools, to eliminate any confusion. . .