I love the colors you chose...and the mobile, and the frames... I get all excited when I see people posting their baby rooms--I'm planning my daughter's toddler room for when we move and I love getting inspiration.
Those wall sticker things that previous posters mentioned are a good idea. My daughter has been ceaselessly fascinated with the jungle animal wall stickers she has next to her changing table, and she's 13 months old!
One thing that I'm glad I did when putting together her room was making a thinly padded area on her floor...I took a queen size egg crate bed pad (bought it at ross, there are probably even cheaper places, too) and folded it in half, then sewed a really simple cover for it using colorful cotton duck cloth. I put it in the corner of her room and added a few pillows, figuring that it would make playing on the floor more comfortable. She has fallen asleep on it a few times while playing in her room. Maybe its too
. It adds color to the room, and its a nice place for me to sit while I'm playing with her on the floor. I also ended up using it as a bed for many nights in a row when she was first born and I was nursing her constantly (she was a finicky nurser and my milk supply never seemed like enough, I had to nurse really frequently during the first 2 months...sorry, tmi).
painting thrift store shelves/dressers always brightens things up, too...