Maybe it was because of the Mercutio thread, but I first thought of Shakespeare's play when I saw the topic title. While I'm not a fan of the name, I think the sound and look of Timon is pleasing enough, and it has a positive meaning. Though uncommon, it's not too exotic or unusual, and it would easily fit in with the more popular names. However, I do think many people would associate it with the Lion King meerkat. In any other case I would judge it usable, but I have some reservations about deeming it so because of that connection.
Are kids these days familiar with the Lion King at all? I think those born in the eighties/nineties and their parents would get the reference, but I don't know if it's very popular anymore.