What do you think the most useful plugin is on your blog?

[Liberty]

Wordpress.com stats

[Ryah Albatros]

Another vote for Wordpress.com Stats, and then I can't choose! I like Disqus comments, SEO Slugs, Yet Another Related Posts, Exclude Pages, Contact Form 7, TweetMeme, Akismet, Add To Any, FV All In One SEO, Wordpress DB Backup - oh I'll just list the lot shall I?

[artizhay]

More of a backend plugin, but my favorite is Shorten2ping.

In collaboration with my install of YOURLS, it creates a short URL like site.com/u/2 instead of site.com/2010/08/life/some-long-title-goes-here. I like this so much more than services like bit.ly because it creates a link to YOUR site rather than bit.ly which then goes to your site.

To make it even better, it send an update in the format of "Title-goes-here site.com/u/2" to ping.fm which then sends that out to about 15 different social sites I have on there.

It is extremely useful for getting exposure and traffic. On blog post days, I get a big spike in traffic from curious people.

If anyone wants to try this out and needs help installing it, let me know. It's easy to use if you use things like bit.ly, but for YOURLS, it's a custom install so some people may struggle with it.

[Fabster]

All in one seo and xml sitemaps, given on all my wp installations

[TheLinkMedic]

The custom html/javascript plugin

The built in ones are nice but I always like some good ole html and scripts.

[xMuku]

I'd have to go with the rss feed for my blog, sits to the right of my posts

[kuld33p]

I love

WP Super Cache
Widget Logic (this one is amazing, so much customization possible now)
Ad blocks
Similar Posts
Header Footer
WP CSS
WP Page Views
Query Post

These are some of the ones I use with the fastest wordpress theme in the world.