I haven't really gotten a chance to look at the plugins that are out there - there seems to be a ton of them though. The few I've picked up for my WP site are:
Static Front Page - This lets you set any page as a front page in case you wanted a site intro or something of the sort.
intouch - The only contact form plugin I've had that works for me.
Akismet - This comes with all of them (I think) but make sure you activate it. Great spam blocker.
wp-icq-status - Shows your icq status although I can't get mine to work for the life of me. In theory it's a good plugin and plenty of other people have it working though :p