We spent years trying out the various tools that would show us where our client's websites stood on the major search engines - and WebPosition turned out to be just right. Since 2004 we have ran it on our in-house server and served up reports internally to our clients.
This summer, WebPosition announced a shift in their business plan and moved their product to an SaaS model. They now offer up all the great research and reporting features from within a web interface - and they host all the reports as well.
The new reporting interface is quick and easy to use, and the data collected helps us keep dibs on where you stand organically against your competitors.

The pricing model is affordable and lets us dip our toes in the water with a monthly report on a small website, or go hog wild and scan the top 3 search engines.
We have had great success in the past with their software product and hope to get even more insight into our Search Engine Optimization efforts going forward!