I was getting ready for my housemate's Star Wars game today and the thought occurred to me that gaming books are really heavy. A single gaming book isn't that big of a problem, but when you stack up 3, 4, 5, or the 10-12 that some systems build up to it gets quite burdensome. The books are large. Their size makes them awkward to carry. And then, well, there is the simple fact that all those covers and pages loaded down with ink and text and art gets very very heavy.
So what do you do?
Some games, like Pathfinder and FATE Core, have awesome System Resource Documents or SRDs online that are available for use. These things are amazing, holding all the rules, tables, charts, and other stuff you need mechanically for a game online. All you need to access them is a computer - or tablet or mobile device with a web browser - and an internet connection. You're still supposed to own the books - that is what the company asks - but it frees you from having to carry them around with you all the time.
Other games have PDF versions for sale. Some companies will give you a PDF copy along with your physical copy when you buy it. Others just distribute electronic copies either through their own store directly or through places like Drive Thru RPG. While not quite as efficient for use as an SRD, this still lets you carry around a 1-3lb computer, or tablet again, instead of 20-40lbs of books and just load it up with PDFs. You then have to flip through the PDF books like a regular book to get the data, and you have to deal with reading on a screen for a lot of things, but it still helps on sheer portability.
Unfortunately, some games - like the originally mentioned Star Wars game - do not have an official PDF version. This makes things harder. Your left with either hauling all the books, cherry picking the ones you think are most useful and risking being without the table/chart/thing you need. Alternatively, you can turn to unofficial PDF copies. Morally, if you own the book, I see nothing wrong with owning a PDF copy as backup. However, as there are not official releases you often do have to support - at least in part - the pirate community to get the PDFs and that can, ultimately, hurt the game you love. Because of that I don't like doing this, nor do I, or will I, provide links to places for it.
Finally, I suppose, you could always make your own electronic version of the stuff you need or even physical cheat sheets. Many GM screens are good places for hosting often needed tables, charts, and quick reference rule tabs. Others have players heavily customize them for just that purpose.
What do you do? How do you handle the physical burden a well developed system can bring?