Yes, you can now compile your C# or VB.NET code online, simply put your code in the provided text box and click “Compile Now” button. Compilr will compile your code and provide you the link as well to download complied version of your code. Any error while compilation will display error message on page.
URL: Compilr

Interresting!
So, how do we know that the binaries are not infected with virus?
If someone come up with any innovative idea and takes all pain to push (and then later maintain) it online, than I usually presume that they have good intention behind. But you can verify generated binary using MSIL Disassembler (Ildasm.exe).
Good question though!
The origional site is no longer online. Another similar site seems to have popped up at compilr.com.
complir requires an account. I have too many accounts.
to mc:
So true.