Sendoso does this too, but they have long lead times (3-4 months). They can do it with both official Lego brand blocks or no-name blocks (Lego compatible) for a cheaper price, and can do custom packaging as well.
Ooh one of my clients did monogrammed backpacks at one of their conferences (brought the monogramming machine with them.) It was pretty neat and the backpacks were from a client of theirs too 🙂
