Luckily, there are ways to overcome this problem. By changing the tuning of one or several strings of a guitar, we can play combinations of notes that we previously couldn't. Many of these "alternate tunings" have been explored extensively by ambitious musicians (Joni Mitchell claims to have played in 51 different guitar tunings during her career). These alternate tunings open up a whole new world for guitarists willing to look beyond the standard E A D G B E tuning.
Learning to play guitar in many of these new tunings can be an overwhelming task. If you thought learning guitar was tricky enough in standard tuning, you're in for a REAL challenge! Guitarists will have to completely re-learn how to play chords for each new tuning they undertake. For this reason, many guitarists tend to explore one alternate tuning for an extended period, before they turn their attention to another.
Each of the following links will lead to pages designed to teach the basics of a new tuning. Included are tips on getting your guitar into the proper tuning, tabs of songs in that tuning, and links to other resources for that tuning around the web. Enjoy, and watch for more tunings to be added to the list regularly.