(Personally tested and recommended by the author of this web. Some links might lead to other websites.)
While TimeTo is very similar to A&B, there are some terminological differences. Simon, the author of the how to setup GTD with Above and Beyond document, has reposted it to reflect these changes in terminology, in the TimeTo Yahoogroup, where you can discuss other possible setups with fellow users.
For your conveniece, I am also reposting it here: