Besides the tried-and-true recommendation or reference letter that runs about a page and is mailed (or, sometimes, emailed), there is now a new breed of recommendation "letter": brief personal and professional endorsements on business and social networking sites such as LinkedIn, Naymz, Ryze, Fast Pitch!, Spoke, Plaxo and Facebook.
Writing recommendations on these types of sites is easy in one way and hard in another. The letters are short (often just a sentence or two, but more commonly about a paragraph), but it isn't always easy to get across the essence of a person's personality, character and professional skills and attributes in just one paragraph. Thus, writing these types of references should require just as much care as a traditional letter.
Write a draft first. On some sites, such as LinkedIn, the person being recommended will automatically get a chance to approve what you write before it's posted. But to save both of you this back-and-forth and multiple revisions, it might be easier to email a draft for approval before posting.
On LinkedIn, a person's entire work history is often listed. If you've been asked to vouch for someone in a role in which you worked with him or her, go ahead and address that, rather than feeling like you have to weigh in on their current career status or experience. Ideally, a recruiter or potential employer will scroll through the endorsements and collectively those blurbs will result in a clear picture of the person across time. Consider asking the person what he or she would like you to address. For example, if one endorser is focusing on personal traits, you might be best needed as a source for more professional attributes. Don't endorse people you barely know, or have no basis for judging.
LinkedIn style recommendations are by nature a little informal, but still, keep it professional. Don't write like you're emailing a buddy; picture a potential employer reading what you've written. Be specific. Don't just say the person is "smart," say what he or she is good at. Mention projects or achievements you've witnessed. And if you don't feel comfortable vouching for this person, don't do it. First of all, it's misleading. And, in your own sell-interest, remember that unlike a letter that will be filed away in a drawer somewhere, recommendations posted online are there for all to see, indefinitely, unless you revise or withdraw it (an option on LinkedIn's "Manage Recommendations" page).
Also, keep in mind that while it's common for people on the same playing field to "trade" endorsements (you ask your coworker to vouch for you and he or she returns the favor), just like any other reference letter, those on Linked In and similar sites carry more weight if they come from a superior. Finally, if you are actively seeking recommendations from people you could also recommend, be proactive and endorse them first. (On LinkedIn, you can only recommend someone in your network-an existing connection.) And don't give one just to get one; you need to really respect the person.
Index of letter of recommendation templates