I spent (longer) weekend by biking in Šumava national park. Wheather was nice and we visit many interesting places (photos will be online later). But I will never ever make a mistake to travel on MTB with people on treking one, they are simply too fast on road (and they affraid leaving it). If you will be nearby, I can recommend you nice (and quite hard) trip starting at Zadov (where we were accomodated) to Churáňov mountain, then through Nicov to watchtower Javorník, following peak to Kašperk castle and then down Kašperské Hory city and back to Churáňov. It's only 45 km, minimal parts on the road and several nice downhills.
Also this was my first real life experience with geocaching as my friend had GPS there. We found about seven caches, several of them were multicaches where you need to visit several places to calculate final location. Nicest trip was to follow Vchynicko-tetovsky kanal, but finding some stages was quite difficult.
Anyway I'm considering buying GPS, it looks like a good toy :-).