s there such a service that measures the level of crowds you’re most likely to encounter during your vacation in a particular location?

I quite like this. I’m not sure where the data would come from, but I’m sure there’d be some available from different sources.

Is there a Gmaps mash-up/app for public transportation that regards your distance to the station & the possibility of getting there in time?

Again, a really good idea – both the location data & the service information for this one would be a bit more readily available.

Taken from the TwitEye.com idea stream.