skuba - For your future reference, that's called a ranking checker or position analyzer.
Note that you should be careful about confusing rankings with traffic. They might be the same, but not necessarily so. Lots of people rank well on phrases that aren't searched much, so they don't bring in any traffic. Many posts on the forums over the years attest to this.
Also, some ranking checkers are against Google's TOS, so be careful about this as well.