Hotels.com is offering a mail-in rebate valid for up to $100 back on select overnight stays for a limited time. Deal is valid only on trips booked by May 31 for stay through July 31.

Cashback:

• $20 back on 3-night stays
• $30 back on 5-night stays
• $50 back on 8-night stays
• $75 back on 10-night stays
• $100 back on 12-night stays

Hotels.com is also offering 10% off select hotel stays when you use coupon code: 41010 when you book by May 23 and is valid for stays through December 31, 2010.