Each day, Inc.'s reporters scour the Web for the most important and interesting news to entrepreneurs. Here's what we found today.

Stop being stupid on social media. Seriously. We've all heard the stories of people getting fired because of salacious Facebook posts and offensive tweets. Now, companies are getting in on the action too. The Wall Street Journal reports that Reel Grrls, a Seattle-based nonprofit that offers classes for women, tweeted "OMG! @FCC Commissioner Baker voted 2 approve Comcast/NBC merger & is now lving FCC for A JOB AT COMCAST?!? http://su.pr/1trT4z #mediajustice."  Steve Kipp, a Comcast vice president, sent the company an e-mail saying "Given the fact that Comcast has been a major supporter of Reel Grrls for several years now, I am frankly shocked that your organization is slamming us on Twitter…I cannot in good conscience continue to provide you with funding—especially when there are so many other deserving nonprofits in town." In a twist, though, another Comcast VP swooped in and apologized for Kipp's e-mail, and restored funding to the company. The moral? Think before you tweet.

What will Facebook get out of LinkedIn's IPO? Nine billion dollars. That's the valuation of LinkedIn after a strong performance in its first day of trade. That could be great news for the four buzziest other tech companies pondering IPOs: Facebook, Twitter, Groupon, and Zynga. "LinkedIn's performance suggests there is going to be massive excitement around the likes of Facebook, which is even bigger," says Max Wolff, a senior analyst at GreenCrest Capital. When can we expect that? CNNMoney reports that Facebook isn't itching for IPO, but it has said that it will begin filing public financial statements by April 2012—a date that could coincide with going public. While Twitter seems in no rush to offer shares, Groupon's Andrew Mason is rumored to be shopping an IPO around to the big banks.

Y Combinator may have some competition. The Wall Street Journal reports that the SSE Lab, an incubator for young entrepreneurs, is drawing some serious looks from around Silicon Valley.  "In Silicon Valley you're either on the inside or you're not," says Michael Carter, a co-founder of SSE Labs start-up Game Closure. "This program allows students to join the in-crowd without having to spend three years establishing contacts."

Warren Buffet heads to Dunder Mifflin? Warren Buffet made a surprise cameo on last night's episode of "The Office," playing an interviewee for the Regional Manager position at the fictional Scranton, Pennsylvania  paper company, Dunder Mifflin.  The job was previously filled by the lovable doofus Michael Scott, played by Steve Carell, who recently left the show. So how did Buffet do? While the show ended with no one taking the job, Buffet managed to be a convincing as a tough negotiator during his interview  (he was particularly concerned about long-distance call coverage). Other celeb cameos included Jim Carrey, Ray Ramano, and even Will Arnett.

Tips for first-time angel investors. Despite anxieties over the bubble bursting, more and more people are choosing to become angel investors since start-ups need less capital to launch these nowadays. In a column for Mashable, Microventures CEO Bill Clark offers his six most important tips for newbie investors to navigate the treacherous waters of start-up investing. Acknowledging how the majority of start-ups fail, Clark advises investors to understand the high risk associated with each investment, and to spread investments across several start-ups. Most importantly, investing takes patience. "Even if your start-up is successful, it could take five or more years to get your investment back," Clark says.

Proposing? There's an app for that. In your Friday dose of cute, this guy created an Android app to propose to his girlfriend. And it was Harry Potter themed.  Ahh, yes, this is the stuff of sentimental Google commercials.

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