The following deal sites are sites from which I have only purchased from once or twice, so my experience is minimal, but positive.
MamaBargains is a deal site that offers several items throughout the day. There is no knowing when a new deal will pop up. If a deal sells out quickly, it will immediately move onto another deal. If it is selling slowly, they'll put up a new deal after some time has passed. There may be several new deals throughout any given day. The only items I have purchased through this site are a nursing necklace and a "randomness" girl pack (this contained random baby girl items and we loved what we got...a neat towel, socks and CD).
Plum District is a site sort of like Groupon, but for mom's (and dad's too). Most of the items posted are family and baby/kid related. I only recently discovered this site and purchased a "plum steal" for a discount at the Just Between Friends sale in Portland last month. It saved me a few dollars and was easy to use!
Baby Half Off offers a new deal everyday, at half off the original retail price. I just made my first order last Friday...baltic amber teething necklaces for my girls. I have been told they work by several people and figured I would give it a try at the half off price. I have yet to receive my order (although, I just received notification that my order shipped today - Monday). I will have to let you know, when I receive them, how fast the shipping is and how I like the product.
This concludes the list of baby/kid/family deal sites I have used. There are many more out there that I have briefly explored, but have not yet purchased from. Here is a short list of those few I have yet to explore...
Daily Deals for Moms
Juice in the City (Not yet available in Portland)
If you have used any of these, please share your experience. I would love to hear about it!