Does anyone know of any software to draw diagrams/maps? I'm having a "teaching" session and I'd like to have some diagrams to show, one's that aren't my chicken-scratched sketches. Looking for something like the pictures on this webpage perhaps? 

 

You'd be suprised what you can make using Microsoft paint lol

i would think that paint or powerpoint would be adequate enough to illustrate your point

Google Sketchup works well.

If you have a copy, you could use Microsoft Visio.  It would help keep things drawn to scale.

Or keep googling lake maps and the such; print off a picture. You could even send the pic to Staples and they could print it off in a larger size and better quality.

A quick search turned up this list: http://www.cartographersguild.com/software-discussion/1407-list-mapping-software.html

 

And yes, I know it's for D&D/fantasy gaming, but that will probably get you close.

just use ms powerpoint

I would just find a map you like on Google, put it in Powerpoint and add the arrows and text you want to the picture.