I've used them to do labels for a wedding where I brewed a bunch of beer.
They are expensive, but the material is nice, especially if you have to ice the beer down, and worry about the ink running.
You can get the generic labels they have, and they will allow you to pull off and re use.. How long can you pull and remove.. I don't know, never tried. But you can use a wax marker and it'll wipe off.