throw a rock on google and you hit another document management system. But, so far, the only tidbits I was able to glean in systematic manner is “free or not”, “number of google hits” and “underlying platform”.
There is gotta be a better way than installing and getting to work a random sample on my machine just to see which ones are a piece of crud. Where are the intelligently written, non-mercenary reviews? Where are the comparisons? Bitching of the unhappy implementers? Forum flame and holy wars? In short, where is the straight dope?
are you talking enterprise systems like Filenet and Documentum, or something for personal home use?
yes, medium-sized business and up. Personal home use does not pay the bills 
and a wiki is usually more than sufficient for that anyway.
What kind of documents are you managing? For instance technical documents organized library style, or all correspondence within a business?
The cnet or Consumer Reports of the mid-size and up s/w reviews are usually Burton Group, Forrester, and of course Gartner.
Most of these will have the info you need behind a pay wall, but you can get magic quadrant info sometimes.
PS do you really mean document management or ECM? and is this for just digitized docs, stuff born digital, filing for hardcopy, etc?