I don't know about you, but I make good use of Live's only visual mixing aid Spectrum. I always have one on the master. Here are three further visual mixing tools made with Max for Live that can be of great help in your productions.
This Max for Live audio effect gives you a combination of an oscilloscope and an XY scope allows you to analyse the audio signal in both mono or stereo.
This second Max for Live oscilloscope has a floating window feature, so you can look at it either in the device chain or in a size adjustable floating window. It doesn't, however, offer an XY scope or choosing the channels to be displayed.
Simple RMS Meter
This Max for Live audio effect is a simple RMS and phase correlation meter. The two numbers at the top show you the average level of the track for each channel, a very useful feature when you're mastering multiple tracks and want to compare their loudness.
Below that is a standard correlation meter. Correlation values between +1 and 0 indicate that the stereo signal is mono compatible, while negative values indicate out-of-phase material resulting in phase cancellation when played back mono.
This way for heaps more Max for Live devices & tips.