I used to dye my hair black all the time. But yeah, make sure that's what you really want because you can't really dye over it. You have to wait until it grows out.
They have all kinds of stuff now. What I like, being someone who cares deeply about the environment, is the variety of products they have without harsh chemicals that are still semi-permanent. Manic Panic would be something to check out, or Aveda. I'm sure there are others.
But I don't think it's lame at all to dye your hair at any age. I think in this incredibly warped world we have the priorities are skewed and self expression (especially artistic self-expression) should be more highly valued.