Someone I used to work with turned me on to this website when I was complaining about having to constantly write Zoë's name on all her sippy cups and tupperware for lunch and snacks at daycare.
The good people at labelitorloseit.com make waterproof stick-on labels. You can have your child's name or anything else you want printed on them plus you can pick a little icon to add some pizazz. They are essentially an amazing sticker. The best part about these labels is they survive many, many trips through the dishwasher and the microwave, but when you want to remove the label, they come off easily and don't leave any sticky mess behind. You get a set of 60 labels for $13.95. 60 labels could last you for years so it is definitely money well spent.
I haven't tried the iron-on labels yet, but if they are half as good as the stick-on kind, I am sure they are excellent.