Advanced Web Ranking is a nice tool for tracking your rankings across all the search engines. Unlike integrated tools (which I favor), it concentrates solely on rankings, but it does seem to handle the job well. It updates faster than some of the other products I've tried. It also allows you to use both the Google and Yahoo APIs, so you can rest assured that you will be within their TOS when checking your rankings.
You can set up multiple projects (sites), and even schedule the process of checking rankings. There are lots of report options, and customization of reports, which is very nice. You can also let the program figure out what keyword phrases to check based on your website content, and then you can go through the list it comes up with and weed out the ones you don't want. This saves a good bit of time.
Although I'll probably stick with my all-in-one tools, I think Advanced Web Ranking is a good product if you are looking for a rank checker. Check it out at www.advancedwebranking.com.
