In previous blog posts, I've mentioned some of the web-based GPS mapping sites I like to use. One of my favorites right now is the feature-packed EveryTrail. This site lets you do it all, including search and find GPS tracks that others have uploaded that you can download into your GPS device. You can upload your own GPS tracks, either directly from your Garmin device (if you have one), or from a multitude of different file formats that you may have saved on your computer from your GPS, including Google Earth (KML) format.
There's also a "Guides" section, that lets you download detailed travel guides for your next adventure, including the GPS tracks for the route described in the Guide. Check out this Yosemite Valley hiking Guide page.
In addition, there are EveryTrail mobile apps that let you record and save your tracks with your GPS-enabled mobile device, including the iPhone, BlackBerry, Windows Mobile devices, and the Android phone. And, you can easily share your trips on Facebook and Twitter.
I also like all the trip details the application provides about the trips you upload. Not only does it create a map of your GPS tracks, but it also includes trip stats including duration, length, vertical up and down, and even a time slider that let's you play back your trip:
EveryTrail even lets you embed your trips into your blog:
TRT-Tahoe City at EveryTrail
Map created by EveryTrail: Share and Plan your Trips
If you haven't used EveryTrail before, I highly recommend giving it a try. And if you have used it previously, but not for some time, check it out again, as they've made some major improvements to their site.