This is a bit out of my usual writing, but anyway.
I have been looking for good reference management tools. In particular, I needed to attribute tags to references, just as I do for delicious bookmarks. I dont’ want folders, I want tags. I start loving a.nnotate.com because you can tag sentences inside a document.
In fact, even in my laptop I would like to have tags rather than folder. Because too often I use material for different tags.
And tags are great. I usually attribute much more than content-related tags. I add “mustread”, “toread”, “toblog” if its important. I add the name of the project(s) I am using it for. I use for:personname in order to remember the person that I recommend the item to. You can see all this from myTags in delicious.
Anyway back to the topic. I  came out with two stunning ref-mgmt tools, Zotero (hat tip @mpompoli) and Mendeley. Here is my comparison.

  • Tags: they both have it, but they are not interoperable. Is there a standard for tags?
  • Pdf automatic data extraction: both have it, it is a killer application, imagine they extract most relevant metadata from the Pdf in your hard disk
  • Pdf annotation: mendeley has its own reader, which is a bit slow. Zotero instead lets me open files with my reader, which is Skim, where I can easily annotate.
  • Item Recommendations: in both cases, this is starting. It would be a killer app should it work, but I guess it needs a critical mass of data they don’t have. Mendeley is more like a social network, so should do it sooner, but currently recommendations are only based on similar words in the title – useless
  • Web native content: Zotero does it better, but with Mendeley you can import data directly from Amazon
  • Sharing collections: both do it, but I have to use them more intensely to understand what’s better.
  • Local software: both have it, but Zotero is a firefox extension, while Mendeley is stand alone. Mendeley appears more usable to me for this reason.

So in summary, I have a slight preference for Zotero. But I have already tagged so much content on Mendeley and tags are not exportable. So here’s a lesson: no matter if some interoperability is there (both use standard bibilographic format that you can easily import), if user-generated data are not exportable you’re stuck with what you have.
I also think you can see here a beginning of future general tools, such as tag-based archiving and social search.