I was going to start doing my second OS ever. The first one was just a little 16 bit DOS clone. This one I was hoping to make semi-UNIX-Like, but I would like to write it in Ada. My biggest challenge really is that I have not seen any lower level code in Ada. I was thinking that I could just do a tiny kernel in ASM and have everything else be written in Ada... Not my first choice but I would understand HOW to do something like that.

Have any of you ever used strange languages for operating system development?

there is some basics here: http://wiki.osdev.org/Ada_Bare_bones