This is annual report season, taxing the biceps of postal carriers across our great nation, as the companies in which we invest send us fat packages of information.

Much to our mail carriers' dismay, most of us stack those heavy, glossy documents in a corner, or simply toss them out.

It's true that you'll find seemingly boring or inscrutable financial statements in the back of them, packed with numbers in ultra-fine print. But even those are not as cryptic as you might think. You can learn more about the main kinds of reports in these articles:

If even that seems daunting, try a slower, steadier introduction to your annual reports. A casual flip through their shiny pages can provide you with a wealth of information. Here's what I gleaned from my own recent batch of corporate updates:

The stock's recent history might suggest that eBay's glory days are over. It grew 80% in 2004, but then posted big losses in three of the next four years. But the company's annual report contained glimmers of promise, noting that PayPal did more than $60 billion in total payment volume during 2008.

In its letter to shareholders, I would have liked to see eBay management devote more attention to the company's mishaps and missteps. Still, management at least laid out its priorities for beefing up its core business, including making eBay safer and easier, and encouraging PayPal's growth.

International Game Technology (NYSE:IGT)
This maker of slot machines offered readers a nice summary of highlights early in the report, discussing new gaming machines, recent acquisitions, and its deal with MGM Mirage concerning the casino company's CityCenter development.

American Express (NYSE:AXP)
As many companies do, American Express filled the inside front cover with key financial statistics and a few charts. The company has struggled, increasing revenue just 3% while earnings fell by roughly one-third.

Looking further, though, you can see other takeaways. Share buybacks dropped by 94% between 2007 and 2008, which is a shame; given the stock's slump, management could have bought more shares back at a lower price. CEO Kenneth Chenault delivered a surprisingly candid letter to shareholders, forecasting that 2009 will be another difficult year, and stressing that the company is focusing on staying liquid and profitable in this environment, and on positioning itself for further growth.

Berkshire Hathaway (NYSE:BRK-B)
The gold standard for CEO letters to shareholders is pretty much Warren Buffett's annual missive, which usually winds up more than 20 pages long. This year's letter included warnings against the dangers of derivatives, an explanation of the company's involvement with credit default swaps, and a listing of the company's main stock holdings, which include American Express, Kraft Foods (NYSE:KFT), and ConocoPhillips (NYSE:COP).

Buffett also discussed the recent American financial crisis and offered encouraging words about the future. Letters like these can give you a good sense of the character of the managers running companies that interest you. They can also help you understand a company's business and the challenges it faces.

PepsiCo (NYSE:PEP)
I always look forward to PepsiCo's annual report, because it's invariably full of impressive facts and figures. Through just a quick skim, I learned that the company's posted an impressive core return on invested capital of 29%, with overall revenue growing 10% -- not so easy when you're taking in around $40 billion annually.

I was also reminded of the powerful brands in the company, from Tropicana and Quaker Oats to Lay's and Mountain Dew. An easy read of CEO Indra Nooyi's letter will explain the company's response to flagging sales in the Americas -- which includes freshening up the look of the brands and debuting some new drinks.

Make your mail carrier happy
Clearly, annual reports can teach you a lot, even if you don't pore over every page. (The more time you spend with the report, of course, the more you're likely to learn.) As a more informed investor, you'll be less likely to end up surprised by negative developments with your companies. Greater familiarity with your holdings will probably help you sleep better at night, too.

Berkshire Hathaway and eBay are Motley Fool Stock Advisor recommendations. American Express, Berkshire Hathaway, and eBay are Motley Fool Inside Value picks. Kraft Foods and PepsiCo are Motley Fool Income Investor recommendations. The Fool owns shares of American Express and Berkshire Hathaway. Try our investing newsletters free for 30 days.

Longtime Fool contributor Selena Maranjian owns shares of Berkshire Hathaway, International Game Technology, American Express, PepsiCo, and eBay. The Motley Fool is Fools writing for Fools.