In part one of our review of the LinkedIn applications platform, we looked at presentation, file sharing and travel applications that helped you collaborate with your fellow connections on the professional social network.

The late October launch of LinkedIn's application platform ushered in new capabilities for the social network aimed at professionals. LinkedIn decided to start small, adding a list of nine free applications aimed at boosting your productivity and sharing Web content.

The launch of LinkedIn's applications platform on Tuesday indicates that the business-focused social networking site plans to proceed carefully with rolling out new technologies to its professional user base, avoiding the laissez-faire approach espoused by consumer competitors such as Facebook and MySpace.

Within your LinkedIn profile, recommendations, which you must seek out and approve from contacts of your choosing, give employers a fuller view of you as a direct report, boss, colleague, or client. They make your LinkedIn profile more dynamic and personal than the fairly static information (where you worked, what you did) that appears in your general resume.

As the economy falls deeper into recession, many people have turned to LinkedIn, the social network for professionals, to job hunt and connect with contacts who might help them land a new gig. But career experts say your LinkedIn job-hunting efforts will all be for naught if you don't build your profile page properly and ensure that it is search-friendly for potential employers and recruiters.

Building a strong profile on LinkedIn, the social network for professionals, has taken on greater importance as the economy slips deeper into a recession. What information you decide to include, or exclude, could affect future job opportunities as well as your overall identity on the public internet.

Twitter users commonly "retweet" fellow users' tweets or links. You will see a user set off a retweet by using the word retweet itself, or the abbreviation "RT" in front of the message. A retweet can increase the pervasiveness of your message across Twitter, while attracting new followers who might be captivated enough by the tweet or link that you shared to begin following you.

Though it started selling software to universities and small businesses, Google has pervaded more large businesses during the past year with Google Apps, the company's suite of messaging and productivity software. Analysts say Google Enterprise, the division of Google that runs Apps, has added many features to the product that make it more attractive to enterprise IT departments.

Since Twitter limits messages to 140 characters, users have quickly come to depend on "URL shorteners." These free services take the long URLs for links that we find on the Web and shrink them to a manageable, eye-friendly size. Some shortening tools even allow you track the performance (i.e. number of clicks) that a URL receives from Twitter and other social networking services. But all shorteners aren't alike; as I'll show you, some offer more advanced features.

Google Wave, an upcoming Web application that mixes old technologies like e-mail, IM and online documents in a unified, socially-oriented view, could break down the traditional ways in which we compartmentalize and separate information - both as consumers and businesspeople.

Since Google's Chrome Web browser launched last September, it has garnered a small market share (roughly one percent, depending on the study you read). Chrome has embraced a lot of principles that has made the Mozilla Firefox browser so popular: It's fast and open to web developers to improve it.

One of the most fundamental rules of social networking etiquette: You must carefully consider who you "friend" or "connect" with on services like Facebook and LinkedIn. According to career experts, the people with whom you associate, in many ways, reflect upon you.

If you don't go on Twitter for a few days, how do you find the good stuff you missed? Because the stream - the flow of twitter messages (tweets) that moves down your homepage - moves so quickly, it's hard to travel back upstream and find interesting messages.

Twitter is going mainstream. Who would have thought it?

How (and Why) to Get Started on Twitter