Here are some useful tools for working with maps or GPS:
BatchGeo is a website that can generate a map from a list of places in a spreadsheet. This data can then also be exported as a KML file for use in web maps or Google Earth. I used this tool for my EGEA entities map (see the map menu above). I just made a list of cities in Excel, uploaded it to BatchGeo and got the coordinates of all the cities.
GPS Visualizer lets you convert GPX files (GPS positions or tracks) to several other formats for mapping, or convert coordinates to a GPX file. On this website there are also tools to get coordinates based on addresses, or to draw a path on a map and get a GPX based on that path.
Geomidpoint helps you find the midpoint between two positions, or find a place to meet in the middle (say a restaurant). This website can also find random positions, either all over the world, or restricted to an area. These random points can then be used for any kind of sampling or for surveys. Finally this website has a calculator for finding bearings and the distance between two points.
The world coordinate converter lets you convert from any kind of coordinate format to any kind of coordinate format. It also has a wide selection of maps to find the positions you want to convert. It also gives you the postal address of this position.