<dbs> have a dedicated presentation laptop ready on standby
Have laptop powered up, with screensaver off, tested with projector, running OS X (with iWork) and Windows / Parallels (with MS Office & OpenOffice). Also load the presentation laptops with the direct link to the taping/recording software (see http://code4lib.org/node/243 ).
<JodiS> thumbdrives, except for demos
Ask presenters to use canned screencasts when possible (and offer pre-conference links to directions on how to create screencasts)
Turn off Growl.
Provide at least three flip-charts in the lobby area -- one for breakouts, one for lightning talks and one for extra curricular activities.
For the lightning talk flip-chart, pre-mark it with numbers so there aren't too many lightning talks signed up for a particular block in the schedule.
Provide a web service to collect feedback for speakers
Add a "HOWTO have fun" presentation early in the conference to invite more participation