Gurren Lagann, Samurai Champloo, Haruhi, Rurouni Kenshin, Mushishi and Banner of the Stars are really the only ones I've watched a second time in a short period of time. I usually go a year or two before watching the same series over, and relive the wonders because I forgot how it went the first time.
Probably Shuffle!, I have been trying to get around to watching as many animes as I can so I haven't really watched almost any anime multiple times but I would sit down and watch Shuffle! anytime someone asked me if I wanted to.