I have a Rubber Lipped Pleco. He does a good job when he desides things are worth cleaning. He is a great fish. He will stay hidden for a couple weeks and then one day he will completely clean the tank. It will take him 2 to 3 days though.
I also heard that Japanes Algae Eaters are great. Rosy Barbs are also fantastic algae eaters according to AFM Feb 2006.
10 gallon hospital tank.
29 & 50 gallon - High Tech C02 enriched.
50 gallon Pond - Natural.