google adsense allows only 3x. other network for sidebar?

[MeMaBlue]

Hello, I want to ask what other ad-networks you are using. 

Our website is greek so I need the oppinion of clients who have non-english forums. (not all networks have ads that target non-english forums).

The reason i am asking is that i use the 3x allowed googleadsense codes (they work well with greece), on the main forum,

but on desktop i have activated the sidebar and want to put one there too to maximize revenue. 

any tips? 

thank you in advance