Make money on URL shortener site

I've got a link shortener site with roughly 10k visitors a day. Nothing special, no extra functions, just a simple free script and some link building through article directories. Made some good money from AdSense but they decided to ban me and I've had nothing but trouble since. Tried a few different methods but can't even reach a dollar a day even though I used to make around $50 daily.

I'm not interested in getting a new AdSense account so I'm wondering if you've got any ideas or experience about this. What would you recommend without annoying the hell out of the users. Don't want to sink the ship.

Geo IP based cpa banners? Target the 10 countries from which you have the more visitors from. It's very easy, and if you create/find good converting banners, you'll be banking more with it than adsense. Good luck.

A popunder ad for the visitors going trugh a shortened url mabye.

If you've traffic from highly demanded countries then you can try popunder websites like popads.net
I think you can make as much as $5/1k popunders if they're from the US, UK etc.