Have you heard of Giveaway Scout?
They have a great service for bloggers and readers alike.
For bloggers, you submit your blog, if you do giveaways, and they will scour your blog often for giveaways and post them on their site and send out emails with a link to your giveaway for many to see!
As for readers, you can sign up to receive emails of the types of giveaways you are interested in, like mommy stuff or electronics to jewelry, whatever you like. I love this idea, and I get a lot of use out of it.
Check it out for yourself here.