A couple of my favourites -
Bad Behaviour - Spam blocker, works very well in conjunction with Akismet. It means practically no spam gets through now.
Akismet - Default spam blocker which comes with WordPress and does a very good job.
FlickrRSS - A great plugin for showing off your photos which you have uploaded to your Flickr Account.
Brian's Latest Comments - A nice little feature that you can add to the sidebar. It displays a number of posts in order of latest comments. Quite useful.
Contact Form ][ - A nice little contact form with a couple of nice features.
If you want links to these plugins just let me know and I will pop them up, although I would assume that if you searched for them on Google you would have no problem getting them.
Just out of interest, did you create your own theme for WordPress or did you use one and modify it?