I've heard that Googles Adsense is a good way of generating revenue. I'm testing it right now, to see. Other feedback I've heard is good, particularly if you're converting USD to other currencies.

Personally I hate banner advertising but if it works and pays for the site then you can't beat it.

The winning points for me are
* context sensitive, even down to the region the visitor is from
* you can ban your competitors ads!

hth

Sarah