I have 4 boys in 4 different schools nurseries (!!!) and bought an attach a tag after seeing a recommendation in Good Housekeeping: it's fab., my new best friend. the buttons aren't huge but they are secure and fix to most things including shoe laces, there's a remover on the back as well so they are not permanent. I did the boy's uniform pile (and one starts comp, one nursery so you can imagine...) in about 5 minutes.
I bought it direct but i think they have them other places like Amazon as well.
Only think I can;t do is their velcro- trainers as no laces, so ideas of things that actually stay out appreciated!
I recently bought an amazing stamp and ink set from stamptastic. It's a name stamp and some magic ink that will stamp on any surface - fabric, metal, wood etc. I did 2 children's uniform, water bottles, football kit etc in 15 mins which definitely beats sewing in name tapes. So quick i even did their pants!
Their website isn't fully up and running yet but if you email them they'll send you some more info and an order form. A friend emailed it to me.