Software Part Of Speech taggers

Hello,
I'm interested in automated (software) Part of Speech taggers for the English language. Is anyone in this forum interested in them as well?
What I'm wondering about is the best way to compare their accuracy. The problem is that each of the known taggers (see their list at http://www-nlp.stanford.edu/links/statnlp.html) uses its own marker set, some of them can have even more than 100 markers.
Still, most of them claim to achieve accuracy of well over 90%. Does anyone know of some reliable way to compare their accuracy?

Thanks,
PuBu