Finding people whose faces you don't know is also a problem for attendees. Here are a couple of techniques for addressing this and supporting other kinds of peer-to-peer communications:
A `voodoo board' is a message drop for attendees. It's a big cork board covered by a printout of all the pre-registered attendees' names, with a checkbox next to each. Next to the board, place a little table bearing a box of push-pins, an index-card-sized filebox with alphabet dividers, a couple of ballpoint pens, and a bunch of small memo pads.
Instructions posted above the board should explain how to use it. When an attendee arrives, he/she should put a check next to his/her name.
To leave a message, write it on the memo pad and file it in the box under the initial of the recipient's last name. Then put a push-pin next to the name.
To check for messages, just look for a push-pin next to your name. If there is one, retrieve your memo and remove the push-pin.
This setup may be low-tech but it works really well. Ideally, it should be placed just off the daytime focal area of the convention. One of the things it does is prevent the rest of your message boards from getting clogged with person-to-person notices.
Cover a large section of wall with butcher paper. Have felt-tip pens nearby. Mark the top ``GRAFITTI WALL'' in huge bloob letters. Seed it with a few jokes and a cartoon. Stand back...
This is a fun hack I saw at Linux Expo '98 that I'm going to import back to SF fandom. Recognition dots are signals about your interests that you can attach to your convention badge.
Have an easel or section of wall, again covered with butcher paper, marked ``RECOGNITION DOTS -- MAKE UP YOUR OWN''. Nearby, have a table bearing few packets of multicolored gummed-paper dots (all stationery stores carry these), a several felt-tip pens (again in multiple colors), and a scissors.
Seed the display with a few pre-designed recognition dots. For example a red dot with a dollar sign on it might identify Perl fans, or a blue dot with `P' Python fans. A yellow dot with "MS" underneath and an international `forbidden' graphic over it might have ``I hate Microsoft!'' next to it. Or a green dot with "/." on it might be for Slashdot regulars. Or a big roman-numeral two (for the Second Amendment) on a blue dot for geeks with guns.
You want to encourage people to design their own dots for constituencies you didn't think of in advance. People will get very creative and funny about this given half a chance.