If you work with surround audio and want to be able to mute or solo individual channels on a 5.1 or 7.1 track, Cocell Productions has released Somu - a simple plugin with a row of Solo and Mute buttons and nothing else except the simple price of $29.
It is a shame it is only available as an AAX Native plugin as 5.1 and 7.1 are only available to HD users and so an AAX DSP version would be very nice but the extra development costs may be prohibitive for a small developer like Cocell Productions.
We have downloaded the demo and it seems to do what it is designed to do, but note that the demo version produces bursts of pink noise.
When you purchase it you will be able to license up to 3 computers, Macs and/or Windows machines too.
There is talk of a pro version coming along with some gain adjustments too.