I've been scouring the interwebs lately trying to decide what pickup(s) to get to replace the P90 in my Gibson LP Jr., my bridge Tele pickup, and now the soapbar in my lap steel, because I just can't live with that much hum...and there are crazy/expensive options out there.
The Tele wasn't as bad as the two P90 axes but even so I found myself NOT grabbing the Tele because it is not hum cancelling.
I then decided to look into noise gates, etc...only to discover all the hum that I already had, plus (if the threshold was set high) a terribly un-musical clamp-down on the decay. I can't work with that.
Then I stumbled upon the EHX Hum Debugger. Simple design - seems to be a filter that cuts the 60 cycle band. There's a switch for some and more reduction, and that's it. You can hear a bit of an EQ shift when it's on, and a little bit more (akin to the middle-strat positions) when it's on "more" but to kill the hum, it's a no-brainer. I put mine back on my amp and just switch it on when I'm playing an offending guitar.
Yay! Now I can play my single coil guitars more!