G-code (M-code?) for Get Bed Temperature I'm familiar with 3D printing, and the G-code concept. I'm also comfortable with programming. 

Can anyone give me the G-code (or probably the M-code, actually) to read the bed temperature? 

Is there an equivalent of M105 (Get Extruder Temperature)?
M105 should give you the bed temperature.  

For future reference you can find a general list of G/M codes here - RepRap Wiki - G-code. 

Most firmware files include a list, Marlin has it in Marlin_main.  I have no idea how often the list is updated but they don't change often.