Sure, but you need the Mono framework which is not standardly part of other platforms than Windows. So it needs an extra sofware installation.
I think that in C/C++ and under linux you can easily create some little applet to run under terminal.
Also a good idea i think it's to build a localhost site, which you can (with php) dump data from site and modulate in your way

I'm looking for ideas for applications to make and not for programming languages to use ,
C# can run under every platform (OSX , Linux , windows , Android , iOS , Windows phone) . It just require some changing .