Fools were out and about this week in an investing world jam-packed with actions and ideas. Here are three articles you might find useful as you decide how to invest your money.

Does the Market Have a New Nifty 50?
Despite the cool nickname, owning stocks in the so-called Nifty 50 turned out to be bad news for many investors in the 1970s. These large blue chips had been strongly outperforming the market, but "when the recession of 1973 arrived and Wall Street decided that its growth expectations for the Nifty 50 were too optimistic, things got ugly very quickly," Fool contributor Eric Jhonsa wrote.

What about today? Eric says that this time around, the richly valued, outperforming names include rapidly growing tech companies such as VMware (NYSE: VMW), F5 Networks (Nasdaq: FFIV), and NetApp (Nasdaq: NTAP). Even well-established companies such as Amazon.com, Baidu (Nasdaq: BIDU), and Netflix are sporting some lofty valuations right now.

The lesson: "When a group of stocks is priced to perfection, any sign of imperfections will have those stocks taking it on the chin much worse than stocks with more subdued valuations will," Eric wrote.

Read the article to see more about how to keep from getting burned.

Where the Bargains Are Now
If you've been reading the Fool, you know that investing in American companies that do business abroad can be a smart way for investors who are uncomfortable putting money into foreign stocks to take advantage of economic strength outside the United States.

"Global View" columnist Tim Hanson this week made the scenario even sweeter by pointing out that "most of these stocks aren't followed by globally oriented analysts, but rather by industry-specific analysts who don't necessarily grasp or appreciate the international growth opportunities that lie ahead of these firms." He continues: "As a result, foreign exposure within large U.S. companies is going underappreciated and therefore being undervalued by the U.S. investing community."

Buying stocks when they're undervalued is essential to investing success. Check out the article for insight on Johnson & Johnson (NYSE: JNJ) and other stocks from Tim, who is also co-advisor of the Motley Fool Global Gains investing service.

Today's Buy Opportunity: Blue Nile
The Motley Fool ended its special "11 O'Clock Stock" series of 50 stock recommendations in 50 weekdays with a sparkler from Fool co-founder David Gardner, who also leads the team at Motley Fool Rule Breakers.

"Internet retailer Blue Nile (Nasdaq: NILE) might not look cheap, but it continues to prove its worth, and I don't see the company being displaced anytime soon," David wrote.

See the article to find out how owning shares of Blue Nile fit with David's investing principles:

  • "I buy excellence, and it's never cheap."
  • "I go where the trends favor me."
  • "I hold longer than just about anyone I know, which includes 100% of Wall Street."

Look over the full list of recommendations and their performance. The Fool put its money where its mouth is on these picks.