A colleague brought my attention to a freeware called Network Notepad.
I initially overlooked it as being too basic, but it turned out to be actually exactly what I needed: not too big (about 3 MB), not too simple either.
This tool allows you to create an interactive map of your network elements: it is possible to access the network elements (ftp, telnet, http, ...) by selecting their corresponding icon. You can also define custom actions (like launching the CDP Tool).
The icon library may seem somewhat incomplete but, once you discover how simple it is to create your own, this little tool really starts to stand out of the crowd.
All you have to do is to open the object libraries window,
go to File menu > New, and paste pictures of your choice into the empty library space. The object library allows to resize the elements to a proportion suitable for use in a diagram.
Nice alternative:
Draw Anywhere is a Flash based web application to achieve a static diagram. There's is no installation, and the free registration is optional. It also allows you to add your own images.