Copy and paste your LJ Friends List into an update and leave behind an LJ Cut.
If you've met them in person or otherwise know them from the offline world, bold their screenname. If you've only talked to them on the phone (I will include skype here), italicize their name. If you've only talked to them online, leave their name alone. If you have someone on your Friends List who has multiple LJ's, only use one and get rid of the rest from the list.