The bookmarklet should support COinS (like Zotero), so vote for my idea if you like to get citation metadata from sites like GBV (www.gbv.de), Springerlink or citeulike.

Example for COinS:
<span class="Z3988"
title="ctx_ver=Z39.88-2004&amp;
rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;
rft.genre=book&amp;
rft.btitle=Hallo+Welt&amp;
rft.title=Hallo+Welt&amp;
rft.aulast=Mustermann&amp;
rft.aufirst=Max&amp;
rft.au=Max+Mustermann&amp;
rft.date=2005&amp;
rft.pub=Wikipedia-Press&amp;
rft.place=Musterstadt">
</span>