Try "Contact Owner" or Owner Info" in the market....
Owner Info has more features, but requires that you launch the app again each time after a reboot to make it appear on the lock screen. Dev is supposedly working on a fix.
Contact Owner works w/out having to relaunch it after a reboot, but doesn't support Exchange contacts for some reason. (You select a contact in the app to show up on the lock screen, and can add additional info.)
I'm using Owner Info, as it has more flexibility - I'm using all the various fields/info it provides for my own purposes...just entering in what I want to appear rather than following the field labels, so my phone shows my name, my allergy info, and three family members w/phone numbers and request that they be called to return the phone.
You can also select "emergency contacts" on the phone that are accessed from the "Emergency Contacts" button at the bottom of the the PIN lock screen (and I assume the pattern and PW lock screens as well)...I just can't remember where in Settings I did it.
EDIT: Found it...duh....go into Contacts and select the "In case of emergency" option at the top.
Finally, there is a program called ICE: In Case of Emergency, that has all kinds of options to display medical and contact information on the lock screen....I haven't used it with my D2, but did with my D1...it sometimes caused some lock-screen lag, but I haven't used it in quite a while.
