The next person who uses "Maps!" as their example of a mashup, gets slapped.
It seems that everytime someone mentions a new mashup tool, and someone else says "why would i use that? what can I build with that?" the first person quickly comes up with the UNnovative "like a Map... you can mash it up with a map!"... OMG. I remember the day Google launched Maps - it really was incredible to me as a user (and a non-googler). I could finally see the seams in the maps which haunted me on other mapping products.... Then I saw and tried the Maps API... wow... that was enough to get me back into coding for a few seconds (ok, weeks) to create a really cool (from my perspective only) map annotation product... and the Maps API proceeded to draw a crowd... and, YES, really cool mashups! It was early... it was ok to say that... and I remember my favorite was GMaps Pedometer (which was originally posted on this cutsie domain like SueAndPaul.com ;).... So I just revisited it again - and it's still cool! In fact, I just marked off a walk I took while visiting Seattle - to see Pike Market, and the first Starbucks, and some sculpture park, or something... but, hey... looks like it wasn't there when these satellite images were taken...hmmm... anyway - I could easily mark off my route and find that it was 1.24 miles each way (not exactly a thousand miles... but still... it was cold...).
So - I'm thinking now, that mashup site is sooo much fun, that maybe there is room for a couple of more maps mashups. Hold that slap for one or two more mentions.