Some alternate tunings (Google is our friend):
This tuning was once more popular than standard C. Everything is raised an entire step. A, D, F#, B. This is a good one to playing around with...especially if you're playing a piece of music that contains that pesky E chord.
Low G tuning
This style of tuning is becoming more and more popular amongst players. It takes the idea of standard C tuning, but drops the G an octave from a high G to a low G. G, C, E, A. Comes in really handy if you are playing a piece that needs those extra low notes or if you are simply looking for a bigger sound. To tune to this, you need an actual set of strings with a low G like Aquilas.
Slack Key tuning
Mostly used in slack key playing, but can be very useful in a lot situations. The idea is based off the re-entrant C-tuning, with the high A being tuned down to match your high G. G, C, E, G. If you strum the strings with this tuning you'll be playing a C chord.....moving up the fretboard and barring all strings on each fret, you'll be playing the next major chord (1st fret barred = C# major, 2nd fret barred = D major, etc.).
Slide Ukulele tuning
Want to go into the brave new world of slide ukulele? Try G, C, E, Bb tuning. This creates a C7 chord when strummed open and makes for some very fun and bluesy slide ukulele playing.