Wordpress plugins

@ThomasScholz

• Google XML Sitemaps

http://wordpress.org/extend/plugins/...map-generator/
Tells search engines which entries are most relevant.

• HeadSpace2 SEO

http://wordpress.org/extend/plugins/headspace2/
Fine tuning of meta data. Very busy development.

• AddQuicktag

http://wordpress.org/extend/plugins/addquicktag/
Costumizing for the editor.

• Search Everything

http://wordpress.org/extend/plugins/...ch-everything/
Enhances WordPress (poor) internal search engine.

@Paolo Tresso

Shameless plug: my plugin upload+ avoid troubles with non-allowed characters into uploaded file's names.
I think/hope it's worth a look.

http://wordpress.org/extend/plugins/uploadplus/

Other should-have plugins:

• http://wordpress.org/extend/plugins/wp-db-backup/
• http://wordpress.org/extend/plugins/...-one-seo-pack/
• http://wordpress.org/extend/plugins/contact-form-7/
• http://wordpress.org/extend/plugins/...ne-video-pack/
  

@WillKemp

• Statpress is a definite.
• All-in-one SEO pack's worth looking at, as is Headspace2 if you want something more complicated.
• Podcasting.
• WP Security Scan.
• Google XML Sitemaps.
• Akismet.
• One of the contact form plugins. Secure Contact is ok, but its captcha system is practically unusable.

Ewan Lauder

Hello,
At the moment my default install goes.. (plus starting point template)

• RB Internal Links
• Role Manager
• Excerpt Editor (works a treat - so flexible)
• Get Recent Comments
• HeadSpace2 (as above comment - SEO on steroids)
• List category posts

Also quite often -

•  
• NextGEN Gallery
• Post Thumb Revisited
• Executable PHP widget (Caution..)
• Social networking plug-in - um, name escapes me!

And interesting - if not always essential, lol -

• WP Cumulus (mesmerising tag cloud)
• WP-SNAP! (if you need to build a glossary)
• WP Smart Sort (sort posts, categories etc by custom fields you add - fantastic for using Wordpress as CMS)
• Maintenance Mode - privacy on the test server & great for client

Oh, and as Will says, a contact form.

Glenn Haggard

• wp-supercache - converts your website to HTML for faster rendering.
• cforms - great for inserting forms into website.