Seeing that there is some interest, here is another sketch or diagram drawing program.
This program is a common project of Bobbes and my self, and has been discussed and published in the German forum.
http://www.b4x.com/forum/german-forum/2457-elektroschaltplan-zeichen.html
Mamuen had also given intersting suggestions, and uses the same definition for the symbols.
The program allows to draw different kinds of sketches for different topics.
For example electric sketches or network sketches, others are possible and configurable by the user. The network symbols are those of mamuen.
The electric symbols are not finished yet, just a few of them are included at the moment.
The program is almost finished, but needs testing and fine tuning.
There are help files, desktop only, in English and German.
Improvement suggestions and bug reports are welcome.
Best regards.