To ease the transition from bottle to cup for milk, I used the UK version of the cup Sara posted (the spout is the same, but the base differs a little here). Kirsty took it one day then refused it for a few days, so I put it away for a week then re-tried.
To begin with I only used it for breakfast milk, after the week-break she took it and never turned back. I let her use that one for a couple of weeks then started her on a "proper" spouted sippy. Currently we use this one:
Annabel Karmel by Lindam Non Spill Cup - Boots
I had to try and get her from the Nuby to a sippy as she kept biting through the spout on the nuby, but it was a great way to get from bottle to cup as the spout is similar to a bottle teat. (I used the same cup & process to encourage her to drink water from a cup!)
She still has a bottle before bed, and I don't plan to remove it for a while yet, it's more a comfort thing. I don't mind her using it.
My next move is to try her with milk in her sippy for her 3oz milk before her nap (after lunch)