Today's (8/10) deal is $10 ice skating (including rental) at Chelsea Piers indoor ice skating rink. Even though this same deal is available any Sunday during the summer, you can use the Groupon deal any day until November 22, 2009.

Other recent deals have been a massage at a spa, custom tailoring, a pizza waling tour, Alvin Ailey dance classes...

One of the fun things about Groupon is that for each deal a certain number of people have to sign up for it for it to be valid. Although this could be annoying, I think it actually adds a fun, collective spirit. It's as if you are collectively approving the deal.

Another thing to note about Groupon is that you have to buy the item when you sign up. That means if you never end up using it you've lost money rather than saving. So make sure you really plan on using it.

Groupon is available in several other cities as well. Sign up for free at Groupon.com

Do you have a favorite discount or deal site? Leave it in the comments below.