Do you use any article organizers? There is an increasing number of scientific articles which I look through and somehow I feel a lack of a tool to keep track of the already read ones and my summary notes on it. Or another usage scenario would be to search by an author and see which articles of the given author I have already read.

The question is: Do you use or know of any freeware tools for organizing articles?
I used to store them in a SVN repository, and then I found out about Mendeley, quite satisfying so far except for a few bugs. Different features are available depending on whether or not you want to pay some fee, but the free version is enough for many people -- it seems it would be for you.