use wordpress seo by yoast. it's the best. i know about a lot of social plugins but i can't vouch for a 'best' one so wait till someone replies you on that.

At the very least, something for SEO (All in One SEO Pack or Platinum SEO), Google XML Sitemaps, WP Optimize, and Search Terms Tagging 2. I think there's a plugin called Sociable for social media.

Hi Jayuk, I know you asked about plugins in particular, but my theme has pretty much everything you are looking for baked right into the core files (without requiring plugin overhead or management issues)

I do have an on-page SEO plugin called SEO! which operates within the WordPress post editor to help the site owner optimize each of their posts and pages. It works with ANY theme.

In particular though, I think you may be interested in my BizLocal package, which will be released at the end of this month (March 2011). Its specifically tailored to business class websites with all of the items you've mentioned and more.

I've taken my core theme, CE4, and created a package that bolts into it that allows local business consultants to have a turn-key package they can sell to local businesses. It has built in social media integration, lead gen & lead capture optin widgets, slider widget with rotating text and images, and much more stuff to help you close the sell on the first demo.

I've included a pic of "Chicago", one of the 3 pre-configured site packages that will be included with BizLocal when it ships this month. You can take a pre-release sneak peek here > Sneak Peek: CE4 “BizLocal” Package*|*clickbump.com

clicl bump theme is very easy and go for adsense

I enjoy Headspace2.