I have done this many a time when I ran out of beer. two kegs and a fermenter fermenting and an empty keg then transfered the beer and clean the now empty keg, repeat until all kegs are full, three brews at once!
When I started brewing many years ago I used mine a lot.. I removed the injector from the lid, drilled out the hole bigger and fitted a bung with a bubble trap. I bottle anyway, so this way it was put to good use. One word though, it can be a bugger to clean, don't let anything sit in it, clean immediately!
Good advice about racking from Sean ... don't use the tap!
:
Thanks guys for the posts i think ill use it as i tried the plastic keg but it wasn't giving the fizz i like so ill use it as a fermentor from now on, saves me a bit of money