Take a look at the DCC if you haven't already done so.
http://www.rhyolite.com/anti-spam/dcc/

If you're still considering running your own DNSBL...
It ain't free and I can't vouch for the quality, but it's from dorkslayers:
DNSBL in a Box:
http://www.dnsbliab.com/work.html

-- Mike

At 04:46 PM 9/13/01, Bob Tanner wrote:
>Looking for any input from people who are running/using MAPS/ORBS 
>replacements.
>
>My survey shows that the replacements have very small databases, poor web
>frontends, and terrible interfaces to allow removing of entries.
>
>The ones that claim to be open source have not released the source code, don't
>have cvs access, etc..
>
>So, any news in the LUG area about using these?