InformiX
Informix is an important commercial database. It's a direct competitor with Oracle and is designed to support high-end, 24*7 operation. It was merged with Illustra some years ago and claimed to be the first object-relational database on the market. Arguably ahead of Oracle technically but with a smaller share of the market, Informix is still a major player, especially in the Unix database market.
One point often lost on Oracle DBAs? is that Informix has been designed and maintained to require no extensive specialized skills just to keep it running. Any competent Unix/Linux admin can learn Informix quickly and add DBA to her list of appropriate acronyms. Informix doesn't need babysitting.
Until the SQLRelayDA showed up there was scant hope for direct Zope support for Informix. You could have used ODbC, but that implies running Zope on an NT/2000 box. As soon as SQLRelay supports InformiX directly, or for that matter, ODbC on NT/2000, then Zope can stay on your Linux, BSD, or other Unix. BTW SQLRelayDA adds support for many other options as well!
Scant hope becomes reality - a release of a native Informix database adaptor ZInformixDA now exists.