GetClicky [getclicky.com]. I find their interface a bit user unfriendly, could be better designed so that things you need to find are at your fingertips rather than several clicks deep.
There's also OpenTracker [opentracker.net]. On the plus side their interface is well thought out. On the negative side, the people who run it have lousy customer service skills, they can be very rude. So if that's important to you then avoid OpenTracker.