Hi Zaks,
When you say you've 'been successful with google adsense' that's a fairly ambiguous statement. If you're getting a high click rate and high EPC in relation to other sites that you have then the simplest way to increase revenue is to build more traffic.
Check your stats to see what alternative keyphrases people are using to find your site and build pages around those other keyphrases and build backlinks to those new pages.
If you want to try other revenue sources - find some affiliate products in your niche and do some split testing between adsense and affiliate ads. Typically though, your content needs to relate more closely to the affiliate product you are promoting if you want higher conversions.
Thanks,
Dean