Groupon: $20 for $40 Worth at Avis or $25 for $50 at Frontier Flight

Groupon has a couple of great travel deal today:

Get $40 to spend on Rental Cars at Avis for only $20. Valid at more than 2,100 locations in the US and Canada. Minimum 2-day rental and not valid with rewards points, prepaid rates, or previous rentals.

Get $50 to spend on ANY Frontier Flight for only $25. Expires 11/26/11 - must book by expiration day; choose a travel date prior to 2/28/12.