put my ads on other peoples sites? like say im giving them (webmasters) something in exchange for having my adsense ads on their site.... is that against the tos?
No but, you're responsible for whatever happens to the ads. If you get invalid clicks from that site, theres nothing you can do about it.
It's a good idea but what could you offer a webmaster with a good site that he would swap for? If he is getting enough trafic to make it worth your wile putting ads there why would they not do it themselves?
Although as a second thought it might be worth while building sites for local clubs or societies that could promote it to there members, yu build the site for free and get adsense space in return.