Last year when my daughter was about the same age, we got her the Leapfrog Learn & Groove Musical Table. With little ones, you can keep the legs off so they can crawl up to it and play. When they get older, you can put the legs on so they can stand at it. She still plays with this toy, so we've gotten a lot of mileage out of it. It retails for about $45 but Amazon does some interesting pricing things especially around the holidays where prices can fluctuate wildly from one day to the next so we paid $30 with free shipping.
Another good toy we got tons of mileage out of is the Evenflo Exersaucer. It's been ages since my daughter actually sat inside it, but she still walks by it and plays with the toys on it. If they get sick of the toys, Evenflo sells different replacement ones for about $4.