I’ve just bought a load these tags for marking your gear, they’re pretty robust, come in a variety of colours and can have up to 3 lines of text printed on them. I’d got hold of a load several years ago but the original company that made them seemed to disappear, with these guys recently appearing.
The tags are a great way to recover lost kit, I’ve had a couple of karabiners returned to me due to them, and they certainly make sorting your gear out at the end of a training session or trip a lot easier! They’ll set you back £12 (plus £1.10 postage) for the first 2 sheets, each sheet with 44 tags.
Worth a look: http://www.toughtags.co.uk/orderform.html