I have been using this tool http://www.webmaster-gadgets.com to check my Yahoo rankings and find it totally wrong when I check Yahoo itself. I also had a go with this one for MSN http://www.checkrankings.com and some other Search engines and found it to be wrong most of the time as well. Apart from the Digital Point tool what are other people using that is accurate or are they all rubbish.
I use the keyword tool in Web CEO, you have to run it quite slowly but I find it to be effective (particularly as you can check rankings in the geographical results as well as the world).