MindMyHouse is the only house sitting website to have been professionally built, designed, written and edited. We've been online since 2005. Our programmer/designer and content provider/editor have both worked their hearts out to provide you, the customer, with what we hope is the most usable interface and the quickest and most efficient search return possible. You are welcome to shop around on our competitors' sites (if you can find your way around the other sites at all).
The following websites provide a similar service to ours: they're all global in scope, three of the four provide a free service to home owners, house sitters pay an annual fee to advertise their house sitting services.
Note that this list isn't exhaustive. Many more websites exist which purport to be connected with house sitting but they're either unused or unusable, too expensive or for niche groups such as Canadians, seniors or academics only.