I am now the owner of all four collections of Moleskin Maps, produced by +Matt Jackon at Chubby Monster Games, and I wanted to take this opportunity to provide a short comment regarding them.
Mr. Jackson has provided four excellent sets of what appear to be hand-drawn maps (if I understand correctly, they are inspired by maps that he had originally drawn in his Moleskine, thus the name).
There are 11 maps in volumes I & II, and 10 maps each in volumes III & IV. Most of them are underground caverns, although there are also a campsite (possibly two, depending on your interpretation of the map, a small village and a farm in volume I, as well as some other non-underground locations in the other volumes.
Each volume is a pdf with maps, and a location key sheet for the GM to set up what the map is going to represent.
If you visit Matt's blog, you can find samples of his work, to see if you like what you see.
In addition to a nicely laid out pdf, each volume also has a zip file containing high resolution PNG files, which you can use in your virtual table tops, or print out as needed for your not so virtual tabletops.
The price is very reasonable on these, and I highly recommend them to GM's who need some inspiration for locations.