I am deeply biased, as a Romney supporter, but I think this ad, which Romney just started airing in New Hampshire, is very appealing:
Romney seems quite Reaganesque here. By talking about the future and disdaining the past, he also seems to imply that his chief rival in New Hampshire, John McCain, is part of that past. A good ad.
Meanwhile, here's a story about another candidate's TV ad:
Here's more about that pulled Huckabee ad from good old Article VI Blog.