Routeslip.com does not seem to be maintained. There are a couple of active threads discussing it. I recommend mapmyride.com instead anyway as it has flawless integration with Google Earth.

Zooming in can be done in two ways - if you have a wheel/scroll mouse put the pointer where you want to zoom and then scroll in or out. If you do not have a scroll mouse then you will have to click on the +/- tool in the upper right hand side.

You can find out a what at least one other person thinks of a comparision between bikely and mapmyride by visiting http://www.bikeforums.net/showthread...ight=mapmyride. In addition one of the founders of mapmyride has joined the forums, you can read his introductory post here: http://www.bikeforums.net/showthread...ight=mapmyride

Long story short, both tools are really great and I like both.