Often the best resource for car rentals, I rarely check anything else. I also love the “explore” feature for checking out low cost flights for everywhere. This feature isn’t well known on Kayak but I have used it on many occasions to find cheap fares to all sorts of destinations. It displays fares in map format, showing destinations and prices that default to your current location. The default options show all locations, for any length of time, and any available dates and will display the lowest absolute price available for that time.