I just saw this offer over at Sitemeter and maybe it is interesting for somebody out there:
Sign up with MSNs Adcenter (for $5 setup fee) and get $50 in free clicks plus a free Sitemeter Premium account for 1 year.
So even if you are not interested in a web analytics solution this might be a good way to start with Adcenter. Also if you don’t want to spend any money for a web analytics premium service this is an easy way to test their service.
(This posting probably looks like I am getting paid for it, but it is not the case)