WordPress plug-in and widget recommendations needed

I am currently exercising WP and it is a great CMS platform. Anyone recommend me the most efficient plug-ins or widgets to use with ?

Thanks a lot

plugins to achieve what?

Hi ;

Sorry not to mention that. For forum posts, main page layout and seo especially.

plugin for forum depends what Forum software you're running. VBSEO is decent if you use vbulletin - perhaps some PHPBB people can comment on suitable options for that..

What CMS are you using for your main site?

forums and wordpress are not the same thing.

Some plugins ...
twitter tools
headspace
super cache

here are few more plug ins :

All in One SEO Pack
ClickBump SEO!
ILWP Simple Link Cloaker
Akismet
WP SalesAutomator if you are selling an item or 3

All in one seo (already mentioned)
google xml sitemaps (cant live without this one)
wp super cache
seo smart links( lets you link words through out your site)
Widget logic(my new favorite, lets you show widgets where you want them)