I admit it: I buy stocks because it's fun.

Sure, it's nice to invest my daughter's tuition money in a diversified portfolio of individual stocks to make sure my community college budget will someday be able to pay for her Ivy League aspirations. And I can sleep well knowing that my index funds and 401(k) -- which hold the vast majority of my investments -- will continue to increase in value.

But with a small corner of my portfolio, I am able to chase the adrenaline rush that isn't readily available for those of us who have something against bungee jumping, mountain climbing, competitive eating, and all those other activities intentionally designed to put you several steps closer to death.

The money I put into stocks is invested in no small part for the sheer sense of drama. And there's no more dramatic, exciting, get-the-blood-pumping way to invest than in high-growth stocks. I'm buying shares in companies that could be floundering next month, or they could be the world-changing companies of tomorrow.

Consider the case of Charles Schwab (NYSE:SCH), which can be regarded as the very first discount broker. Before Ameritrade (NASDAQ:AMTD), E*Trade (NYSE:ET), JPMorgan's (NYSE:JPM) BrownCo, and the other discount brokers started playing a "how low can you go?" game, Schwab's mission was to empower individual investors and free them from the fees of traditional brokerages. That was risky, to be sure, but that risk has paid off for Schwab -- it's now a $20 billion company.

In fact, according to Ned Davis Research, Schwab was the 13th biggest stock winner from 1989 to 1999. In that 10-year span, Schwab's rise bested such venerable firms as $140 billion chip maker Intel (NASDAQ:INTC), which ranks 33rd on the list (having turned $10,000 into $370,000), and $90 billion home-improvement giant Home Depot (NYSE:HD), which was 34th (with 360% returns) despite having expanded 400% -- from 118 to 930 stores -- during the same period. Investing $10,000 in Schwab in 1989 would have yielded more than $800,000 by 1999. That kind of return shows the power of aligning your portfolio with companies that are willing to break existing rules of commerce and create unprecedented business models. Those returns will also give you an unbelievable adrenaline rush.

Daily dramas
Of course, I'm putting the odds of finding Schwab-esque firms in my favor by aligning my fates with some very smart folks. Scanning the scorecard of the Motley Fool Rule Breakers newsletter service, I can point to an overflowing handful of stocks that have moved more than 25% in a single day -- and the majority of those were on the plus side. The scorecard has seen a few drops -- that's the nature of high-growth investing -- but a lot more have made big upswings. Of the newsletter's 28 formal recommendations, 13 are up more than 20% since they were picked. Eight are up at least 30%. Six of 28 picks are up more than 40%. As an investor in some of those companies, I can tell you that's fun.

Few rides were more enjoyable than the skyrocket by the electronic exchange Archipelago, which is up about 140% since Fool co-founder and Rule Breakers analyst David Gardner originally recommended it in February. I didn't buy that one -- d'oh! -- but I was rooting for it from the sidelines because it was helping turn the Rule Breakers scorecard a very pretty shade of green, after an initial few months in the red.

More recently, a company called Intuitive Surgicalclimbed nearly 25% in one glorious afternoon when the market suddenly got excited by the surgery-performing robots the company makes -- I own that one, so that was a beautiful day! It's more than doubled since David made it an official newsletter pick in April, and it shows no signs of slowing.

Most of the picks on the scorecard have either made a huge leap or appear to be on the verge. There's a Chinese firm I think will be the next of the Rule Breakers picks to deliver one of those adrenaline-pumping days. And I've got my eye on two of the biotech firms on the scorecard -- with FDA approval looming for some of their major drugs, they're about ready to pop. I'm not going to tell you the companies -- have to save those for the subscribers -- but you can take a free, no-obligation look at the scorecard by taking a trial membership.

A world of high-growth opportunities
There are hundreds of companies in a watch list called Rule Breaker Universe that David, his team, and the Rule Breakers online community are analyzing for possible formal consideration. There's a small biopharmaceutical company in Iceland called deCODEGenetics (NASDAQ:DCGN) that is working to isolate key genes and use them to treat common diseases. I'm not ready to invest in it just yet, but the company's DG031 heart attack prevention compound, currently in phase 2 trials, is worth watching.

Yet it's not just dot-com and pharmaceutical stocks that the Rule Breakers team looks for. Any company that grows itself with a competitive advantage by breaking the rules of business is fair game. That can be a drug manufacturer or a company like ZipRealty, which is putting a new spin on home buying. Or Netflix, which fundamentally changed the video store forever.

Any of those innovations could go down in flames, or they could drive the 10-baggers that investors dream about.

How much fun is that?

To take advantage of Fool co-founder David Gardner's aforementioned 30-day free trial, simply click here. The moment you sign up, you'll have full access to everything we've ever published.

This article was originally published on Aug. 16, 2005. It has been updated.

Roger Friedman is the managing editor of newsletters and the author of Nipple Confusion, Uncoordinated Pooping and Spittle: The Life of a Newborn's Father . He owns shares of Intuitive Surgical and Home Depot. Netflix and Schwab are Motley Fool Stock Advisor recommendations. Home Depot is a Motley Fool Inside Value recommendation. JPMorgan is a Motley Fool Income Investor recommendation. The Motley Fool has a fulldisclosure policy.