My fad of the moment, this: OpenStreetMap is a wiki world map.  Why?  Well, the regular world maps are fine but they're copyright material, so there are limits and costs on what you can do with 'em, and they update once a yawnellium.  OSM lets you edit it yourself and do whatever you like with the data.  The online editor is too simple to be fun but the downloadable 'JOSM' editor's a breeze.  You upload GPS traces then draw over them and add POI and metadata as you go.  The editable map is re-rendered midweek so those weekend geo-nerding trips' results are all live by next weekend.

The main online map is kinda dull, but the possibilities are much more entertaining.  Because there are cycle route categories, for example, someone's written a render that highlights cycle routes and minor roads, dims trunk roads, and has bike parking, bike shops and bike hire POI - and made it a Garmin file.  Another chap has piped it as a layer over Blue Marble. 

Of course there arise the usual wiki questions of reliability, completeness and partisan editing.  What if someone goofed?  What if your town isn't there (Crediton mostly isn't, though someone is filling it in now - must have got a GPS for Christmas)?  And what if you've got Aaron123 and Ahmed2009 both editing the hell out of Gaza?  Well, those are all valid questions, but the stunning success of good wiki projects suggests that they're all soluble without too much sweat: correct errors you see; find local rambler zealots and feed them gap lists; apply the mod-stick and lock certain areas.  Right now, it's about where Wikipedia was in 2002, back when you could easily add whole sections, but even so the general coverage is very good. 

It'd make a great class project: draw the local area map as part of a whole local-geography, history-of-maps thing.

My ISP is down.  There is vexation among the masses, particularly as I need one set of contact details soon or a real-world transaction will bork.  C'est la risk of putting a bunch of stuff on a wiki online; it's available everywhere, but it's very unavailable if the ISP does the dying fly.  So I'm sat here like a lemon, fighting the urge to go to treeware despite its many and obvious suckings.

"Munky!  We need more technodgeoly"