It's been a while for me but there was a company that had some really great products that included cups with interchangeable lids. The lids went from nipple, to spout (sippy cup), to straw, and then plain cup. The company was MagMag. It created a great transition for both my DS and DD.
Funny story though, I had kept the cups and the kids' favorite bowls, utensils, etc. for a long time, and my DS who is now 19, stumbled across them about 3 years ago. He was ecstatic! He told me that I had traumatized him by taking away his bottle (he sucked his thumb in his sleep until about 6 years ago, and still has a shred of stinky blanket that he jokingly pulls out every once in a while). Overall, though, he's a good, well-rounded young man now. Actually, now that I think about it, he does tend to keep stuff around a little longer than he should - or maybe it's just the untidy man thing. LOL!