Ah, Fidelity. So great when it's good, such a drag when it isn't.

Now now, I'm not talking about that kind of fidelity. I'm talking about Fidelity Investments, the mutual-fund-discount-brokerage-and-all-kinds-of-other-stuff colossus that looms large over so many people's portfolios, especially their retirement portfolios.

Retirement, after all, is a huge part of Fidelity's business nowadays. In addition to the thousands of plans that include Fidelity funds as investment options, Fidelity provides the administrative backbone for many 401(k) and 403(b) plans, including those of huge companies like Ford (NYSE:F), Pfizer (NYSE:PFE), and Merck (NYSE:MRK).

Fidelity funds are also part of many individual investors' strategies -- with hundreds of actively-managed funds covering all corners of the investing universe, they're kind of hard to miss.

With ubiquity comes … mediocrity?
And that's sort of the problem. While Fidelity's funds seem to be everywhere, their performance is all too often mid-pack at best. They have hundreds of funds, but very few seem to stand out. While Fidelity was once the darling of the mutual fund industry, concerns about management turnover and high fees -- and in recent years, sub-par returns -- have dulled their reputation in recent years.

Nowadays, in a world of ETFs and index funds, where active management is often considered a negative, Fidelity funds are often an afterthought -- except in those retirement plans. And that's too bad, because there are still some terrific products in Fidelity's fund lineup.

Some stars still shine
Take Fidelity Contrafund (FCNTX). Despite its name, it hasn't really been a "contrarian" fund in decades. But that's okay -- instead, since 1990, it has been the focus of manager Will Danoff's considerable investing skills. Danoff tends to look for large-ish names with substantial growth potential -- stocks like Google (NASDAQ:GOOG) and Genentech (NYSE:DNA) are among the fund's biggest holdings. Turnover -- a perennial challenge for Fidelity -- is low by the company's standards, fees are reasonable, and Danoff's steady, research-driven style tends to keep the fund out of potholes. If it's an option in your plan, grab it.

Another fund worth a look is Fidelity Low-Priced Stock (FLPSX), the domain of manager Joel Tillinghast for almost two decades. Essentially a mid-cap value fund, Low-Priced Stock's portfolio is full of solid, financially stable -- but out-of-favor -- companies like Bed Bath & Beyond (NASDAQ:BBBY) and Coventry Health Care (NYSE:CVH). Turnover is low and long-term performance has been excellent. If this one's in your plan, it also deserves serious consideration.

A map to the best of Fidelity
Fidelity has a number of other funds, including many less-well-known names that are worth serious consideration. Of course, it also has some clunkers, too -- and some of the clunkers are featured options in many retirement plans. What's worse, a few of those clunkers look like stars at first glance -- and sometimes at second and third glance, too.

If Fidelity products are prominent in your retirement plan, knowing the company's quirks and the ins and outs of their key products is essential to maximizing your long-term returns. My fellow Fool Amanda Kish, our resident mutual fund wizard and lead advisor of the Fool's Champion Funds newsletter, just put together a special report on Fidelity's funds that walks through the lineup's high and low points -- and explains how to assemble a great retirement portfolio when Fidelity funds are your only options.

Want to take a look? Access to Amanda's new report on Fidelity is completely free with a 30-day trial of Champion Funds. When you sign up, you'll also get reviews and insights on funds from dozens of families, and tips on making the most of whatever your retirement plan gives you. Accepting your free trial only takes a moment, and there's no obligation to subscribe -- click now.