In preparation for my PhD, I recently started investigating Mac OS X tools for managing BibTeX-based bibliographies.
In the end I settled on BibDesk. I chose it because of its functional merits but it's great that it also turns out to be open source.
Because BibDesk allows me to link from an entry to a file on my local filesystem, I can just put all my PDFs in one directory and use BibDesk as the interface to all the papers.
One thing that I don't believe is supported (yet) but which I would like to use as work on my literature review continues is the ability to express relationships between entries, perhaps along the lines I talked about in Google Scholar and Typed Citations.
Of course, then I'd like to express relationships between other entities such as authors and maybe concepts, terminology, etc.
Actually, a lot of the features I'd like to see in BibDesk are features I'd like to see in any MicroContent browser. After all, that's what BibDesk really is.
The original post had 2 comments I'm in the process of migrating over.