local interest GPS

I don't travel particularly widely but when I do I always find myself wondering what things are and why they're there. Take London for instance - there's a statue at the bottom of Charing Cross Road next to the National Gallery of a woman that I think is Florence Nightingale but I can't be sure, anyway the inscription says 'Humanity'. Why's that there? what's the significance? And I was stuck on a train the other day, looked out and we were in a railway cutting with the rock layers really well exposed at the sides (being a geologist, this caught my attention lots).

What I would like to own is a GPS thingy that works out where I am (and yes, I'd pay more to have it work out my exact location within about 10 metres), and gives me a list of options to find out what I'm near. Landmarks, museums, places where there's a nice view, what type and age of rock I'm standing on, and corresponding links to encyclopaedic websites to find out more (if it was also, or was linked to, a PDA). Would be easier than things we can already have like location-specific traffic/weather/news updates, because the information does not change. There's just more of it. Further development could include "I am at this location - where are the nearest sites of flora/fauna interest?"

And if you tell me it's baked, please tell me where to get one, and how much they cost. Thank you lots.