Alternatives to Endnote and CiteULike?

I've just posted a question about useful alternatives to research citation manager tools such as Endnote or CiteULike to the AoIR mailing-list, and I thought I'd repeat it here as well. My approach to research is to store key quotations from a source alongside the bibliographic reference, but none of the standard tools I have come across seem to do this particularly effectively (e.g. in Endnote, the best available workaround appears to be to create an additional field for quotes in the bibliographic record, but this is clunky and doesn't work very well with multiple quotes stored against the same record).

My preferred workflow would be a two-step process:

1. Create a primary bibliographic record for the source, e.g.
   
   [2] Graham Meikle. Future Active: Media Activism and the Internet. New York: Routledge, 2002.
   
   
2. Create (multiple) quotations as secondary records stored against the primary one, e.g.
   
   [2.1] “People who hope to draw attention to issues can use the Net in a host of ways, but few are effective without the eventual participation of the older media.