Getting lost is never fun. Having to stop and pull out a map or ask for directions can be frustrting and slow down a good day's ride. Global Positioning System (GPS) devices have been around since the 1980s when they were used mostly for outdoor recreation. Only recently have they become very popular accessories in automobiles, and standard equipment on many boats.
I've got a Garmin Nuvi 255 with handlebar bracket, waterproof cover and car type cigarette lighter connection to battery. It's brilliant - only a 3.5" screen but very clear, easy to follow, warns you of speed traps and recalculates quickly if you miss a turning etc.. Great for £80, highly recommended