I like the following two LinkedIn Apps the most for sheer usefulness. Â Try them out - the blog gets extra readers and Company Buzz helps you track company. See them right below the all new LinkedIn inbox.
The link below takes you to the Application Directory.
http://www.linkedin.com/static?key=application_directory
My Wordpress blog helps me when I want to post an article to one of the 50 groups. I use the Add to Any button from  and click share on LinkedIn.
LinkedIn is quite convenient for sharing ( but be careful of overdoing it -lest it goes spam)
I use the Company Buzz with a slight twist though. By using broad keywords I get a list of, say, people I want to follow in the world of data mining or business intelligence.
Next I follow NOT the people following the influential tweeters, but the people who they are using RT or messaging replies @.
Hope this helps your LinkedIn account. You can send me a LinkedIn Invite at www.linkedin.com/in/ajayohri .
And do take part in the Social Media School group on LinkedIn here http://www.linkedin.com/groups?gid=1854626