Serving a mix

how do i start alternating adsense and other ads?

[loudspeaker]

I'd like to start mixing adsense ads and other ads (affiliate, 3rd party networks, house ads, whatever).

I am basically looking for a server (ideally, externally hosted, but I'll also consider installing a software package) that would take HTML code for the various programs and give me a single URL of an ad block to put on the page.

The block would display something like that (just an example):

40% of AdSense
30% of House Ads
20% of Affiliate Ads
10% of other network ads

My question is very simple: where do I start? Are there any good 3rd party serving solutions that will do that for me, preferably with reporting? Are they expensive? Would you mind sharing positive/negative experience?

(If URL's are not allowed, the names will suffice)

Thanks a lot!

[javahava]

open ads is free and decent. their user interface is a bit awkward, but once you get used to it, it works.