You could look at something like Slashcode (used by Slashdot):

[slashcode.com...]

However, it's not an easy system to set up unless you have some good experience with Perl.

There's also a beta, open source project called pligg that has similar features to digg.

I have also seen another community using such a system, infact looks better than digg [ampminsure.org...] , it has tagging and view concept too.

You can try asking their community innovation center team for code, they look very open to such requests.

Another one as mentioned is [pligg.com...] . You can also try [talkingpixels.org...] .

Thanks,
AjiNIMC