Tracey is a Java-based graphical GPX trace upload program. It allows you to choose any number of files from your machine and upload them to OpenStreetMap without having to go through the web interface.
Tracey uploads all the files you select with the same description, tags and privacy setting.
Tracey's source code is in the OSM Subversion repo at http://svn.openstreetmap.org/applications/utils/gps-tracks/tracey/ -- or rather the project is. Tracey was written using NetBeans, and you'll find it easiest to build, hack and contribute to Tracey if you do, as well. The code itself is all GPL v2.0, even if it doesn't say so in the files yet.
You can still build Tracey using ant even if you don't use NetBeans.