Android Market advertising

When I submitted my first app 'Backgr' into the Android Market I was really proud of myself (I'm still too).
My first ever Android app born in less than a week (only 5 days of works), I needed to update it a bit (improve probably is the right word), but then finally was on the Market.
Then I decided to add advertising into my app, just because I had to pay an entry fee to Google and I want to be 'refunded' (in some way) by adv impressions.
Unfortunately, adMob doesn't support this feature. This means I need my users to click on the adv to earn some money. I think this is not the right way to earn money, because as a user (and not only a developer) I never click on in-app advertising.
adMob advertising is still into my app but it's almost useless right now, just because my total active users are only two: a friend of mine and myself.

My real problem right now rely on the lack of users, the need to spread my app around the world and I have to find the right way, without paying anything.

I think I'm going to ask some bloggers to help me in my 'mission'.
Let me know if somebody out there is interested