The easiest labels to remove by far is Hoegaarden. A quick soak and they come right off. Others are not so kind. Soak in the sink with hot soapy water for at least an hour, some require overnight. Some labels fall right off, some require scraping with a knife or razor blade. Once most of the label is removed, the remaining glue can be removed by scrubbing with a scouring pad. Some people swear by PBW, and it may work the best, but dish soap is ALOT cheaper and works just fine. Make sure you rinse very well.
There is good info on this in the label thread (sticky too if I'm not mistaken). Normally hot water soak, fingernail for the label (if they don't fall off), and 3M scratchy for the goo works great for me.
Second that. Easy and effortless, even on those stubborn labels.
I usually pull hot water right of the hose bib drain for my waterheater, and if you use it often enough, it also keeps the sediment deposits flushed out of the tank
Just cleaned/removed two cases worth of lables today. Mostly Sam Adams and some Michelob. Sammy's were pretty easy just soaking in hot water and then giving them a nice scrub with a towel to get the glue. Might try the oxy clean next time to make sure all the glue is off. They will work for now. Michelob's were a bit tougher.
All this being said I definitely came to this section of the forum to start reading up on kegging cause bottling just doesn't do it for me!