Frigidaire 8.8 cu ft. 4 five gallon kegs fit comfortably (don't think 5 would fit, but not sure since I only have 4 to try out). I also have a Frigidaire 7.2 cu ft model (fits 3 kegs, definitely not 4) which used to be my kegerator until I received the 8.8 model. I plan on using the 7.2 as a temp-controlled container, it looks to be plenty big enough for my 6.5 gal glass carboy.
My advice to you...(aside from drinking heavily) is to measure the interior dimensions of any freezer you might be looking to buy to make sure it will meet your expectations. I got my first freezer from Craigslist, which is a great way to find deals if you have the patience to wait for the right thing to come along.