The Relation Analyzer (http://ra.osmsurround.org/) analyses OSM relations for several quality-assurance-related aspects: (amongst others) relation on a map with segments' start and end marked, warning if the relation has gaps accompanied by a list of the segments if there are gaps, a height profile, type of ways included, tags.
This is useful for all kinds of routes, including routes that are currently being surveyed. On the European continent alone there are more than 70,000 relations (May 2009). During general editing processes relations often get destroyed by inexperienced users. The Relation Analyzer is useful for keeping an eye on a relation and immediately helps you to identify errors.
At the same time you can extract a relation as a GPX or KML file for your GPS device or view it directly in the OSM map. The export for navigation only makes sense if the relation is in one piece. Additionally it supports the JOSM RemoteControl, so you can find and fix the relation gaps (bugs) right away! Use the search function to find a relation by name.
For known cycle routes in Germany check WikiProject Germany/Radfernwege. There you can find already defined relation IDs.
The current version uses the latest (0.6) OSM API.
You can use a bookmarklet to make accessing the analyse pages faster: /Bookmarklet.