Thanks everyone!
fishkeeper - Silver dollars are extremely peaceful. They are a schooling fish. Unfortunately, I know a lot more about them now than when I got them (my bad - I trusted the lfs), so I presently only have two. The next time I can get one in my town, I'll add another. They're very shy and can be quite skittish if kept in groups less than minimum three, although I've seen some people say they'd never keep less than five or six together. It took mine YEARS to settle in, and then I moved them to a bigger tank >.< . It's been about two months since the transfer and they're back to normal (finally), and will actually eat out of my hand if I offer something good enough. They're quite herbivorous, and will make a meal out of many of the plants in their tank, making aquascaping extra challenging. Also, they get rather huge - I've read everything from 8" - 12" in diameter. My larger one is presently about 6". At any rate, if you have the space to house them, I'd highly recommend silver dollars. Their irredescence when they swim is breathtaking.