As for the AdSense / hosting costs...
How much data transfer do we have? - I remember it being something huge like 500GB a month, and we'd have to have quite a lot more visits to reach that (I'd be surprised if we're even near 10% of that at the moment.)
I think pushing the affiliate stuff is more likely to boost income than AdSense - how many people actually follow AdSense vs affiliate links?
Oh, can you see what they can do about upgrading us / moving to a new server as well?
Upgrading Apache, MySQL and PHP at least would be nice, but a whole new server that someone actually supports would be better. Something less archaic than Redhat 3AS, which not even Redhat support anymore it seems.