I have really been impressed by Kayak. They get rave reviews from everyone who use them. Probably because they only give information; they don't fly airplanes nor even sell flights. They are a travel search engine that makes it easy to find and compare everyone's rates--traditional airlines and "no frills" alike. You can not go wrong by trying Kayak. They will save you time as well as money.
There are too many features to list--just take them for a test run.
(Register for a free account for added services.)