www.evreward.com
www.cashbackchart.com
www.rewardsdb.com
evreward.com has a good search tool (you don't have type the merchant name perfectly). It also has current coupon codes listed. It doesn't have all Sign-on bonuses listed. I like this the best.
rewardsdb.com isn't accurate (so check the actual site before making a purchase) It also reviews and New memeber bonuses (no accurate iether) listed on the site
cashbackchart.com is big chart. It's great way to get quick information.
Various Cash Back Site that have sign-on bonuses:
Mr. Rebates - Gives a $7.50 signing bonus. You can request check at $10 (minimum).
Ebates - Gives a $5.00 bonus. Cashout at $5.01.
Cashbaq - Gives a $5.00 bonus. You can request check at $10 (minimum).
SendEarnings: Not recommended, since Cashout is at $30. Check out the Review