Latest version of the WCA competition Score sheet can be downloaded here:
WCA competition Score sheet.
WCA highly recommends Cube Comps, an online system with live scoring and lots of interesting features, like score sheet printing and a very user friendly multi-user score entering system. Created by Luis J. Iáñez and now under Open Source.
Another option is Live Results by Jim Mertens. It is based on an Excel file, that can be uploaded to a web server.