I use Ebates all the time and I get 30 cents here, $5 there... it all adds up. Just the other day I made a large purchase and a medium purchase on the same day. I received an email on my medium purchase (You just earned...) but not for my larger purchase. I went directly to ebates and asked "Where's my cash" on their help page. Well... I got an immediate response, an immediate credit for my purchase on my account and a kindly worded explanation the the web site I purchased from often takes a bit longer to tell them about a completed sale.
I always get a timely, friendly response and over and over I am pleased with my shopping experience. Cash back is AWESOME! They really do send you a check! DO IT! Sign up! They are fabulous!