If there is one thing I know, it is that people like lists. People also enjoy reading things about the social news site digg.com. Why not combine the two? Here is my list of sites which infringe on the digg trademark:
DiggGames.com (now games1.org) - collected the flash games which made it to the homepage
Digg2phone.com - (closing) - follow specified digg stories with text messages
Diggcard.com - (closed) - allowed users to create a miniature profile cards for their website
Diggdot.us - (now doggdot.us) - an aggregator of digg, del.icio.us, and slashdot articles
DiggSig.com - create your very own automatic updating Digg Signature for your website, myspace or online forums
DiggAddict.com - News and/or controversy news about digg.com
Diggirc.com - connect with other diggers via irc
Diggscape.net - aggregates rss feeds from digg, netscape, and now reddit
pocketdigg.com - digg's and many other sites' headlines formatted for mobile devices
duggtrends.com - a site which compliments digg by mirroring dead links, also includes several other neat features
DiggLicious.com - hybrid digg + del.icio.us in a digg spy scroller
diggsoundboard.com - parody 'comment cloud' of digg comments
diggvsdot.com - highlights crossposted articles from digg and slashdot and scores them
slashdigg.com - half digg, half slashdot
diggfiltr.com - create a custom digg feed in seconds
diggfans.com - forum-ish thing that doesn't really do anything
diggdown.net - site that offers mirrors of diggnation saturday night - tuesday night
diggarmy.com - website that spells 'digg army' in the little digg guys, pretty creative
dugg.mobi - mobile friendly digg.com, soon to offer mobile friendly site conversion
dugged.com - help fix this person cat, saw this posted to digg
I am pretty sure I was able to find most of them myself, but if there are any other please let me know. Have any more sites been contacted to be shut down?
On a side note, several of the services listed above are mobile version of digg. Digg already offers a service that does that. It can be found at diggriver.com.
I should also mention that I DO feel that digg has the right to go after sites that use the digg trademark, especially if they are using digg graphics making the site appear like it might be associated with digg.com.