If you absolutely need to keep beer outside of the refrigerator, buy it from the distributor or grocery store warm. You will notice the difference b/w a beer gone from cold, warm, cold, as opposed to always ice cold.
It'll certainly loose some freshness...but nothing like taking a case of beer out of the fridge, putting it in the trunk of somebodies car for three days in 95+ degree heat, and then putting it back in a fridge.
It seems to depend on the brand. Once I had some Coors Light that went from room temp, to frozen, back to room temp, back to cold. Tasted normal. I've had Labatt's Blue (now known as Labatt Blue) that went cold/warm/cold and you could tell it was skunky the moment you popped the top.