I just discovered a cool GPS track editing and planning tool for Mac OS X, it’s called TrailRunner (http://www.trailrunnerx.com). Have been playing with just for an hour trying to plan a hiking tour for 1st of May and are quite amazed how many features are included and how well it is designed.
It has integrated several online map services (Google, Openstreetmap, Bing, …) to show your tracks on road maps, terrain maps and satellite or aerial photos.