Last minute is usually quite good
lastminute.com: hotels, holidays, flights, travel and entertainment at the last minute. - It allows you to build your own ideal vacation ( hotel , flight, car etc..)
Otherwise try Travelsupermarket
travelsupermarket.com - the travel comparison site a good comparison site.
If you are looking for something a bit more "exotic" but not too far away from Europe , I would recommend Marrakech ( Morocco in general- stay in a traditional riad ,much nicer than an impersonal hotel ) as the flight is not too long. Madeira is also lovely ( not sure it counts as "exotic" as such) , as is Croatia. The Euro-Zone is really prohibitive at the moment though ( hence Marrakech being an excellent destination also).
Cape Verde off the Coast of Africa is superb too but it does take a while to get there.
Tourisme à Marrakech, Riad, Hotel, Restaurant, Spa, Locations à Marrakech
Cape Verde Travel Information and Travel Guide - Lonely Planet