KBibtex is a useful bibtex bibliography management tool for the KDE desktop.
However, it seems that the package is missing in the Ubuntu 11.10 repositories.
A quick remedy (as tweeted here) is to install the package from the Debian Sid distribution: kbibtex.
To install on the command line (check the exact name of the .deb file)
sudo dpkg -i kbibtex_0.4-1_amd64.deb
Alternatively .deb packages can be installed in the GUI (e.g. by opening the file in Dolphin).
The package should be compatible with Ubuntu 11.10, and seems to work fine.
The 0.4 version has improved a lot and has a very useful online search tool for acquiring bibtex files. Google scholar and other data bases can be used.
Other tools include a reference preview (though bibtex2html) and a PDF preview.