I've always loved P-90s. I had a Reverend 290 with their version that was cool, but it didn't have the LP Junior crunch.
My Les Paul has Skatterbranes in it that are great, and I've been playing my Strat a lot lately with Lindy Fralin Vintage Hots in it. I put an SP 42 in the bridge and it sounds P-90ish, but man, there is nothing like a great LP Junior with vintage P-90's thru an old Marshall. THE classic rock sound if ya ask me
Oh and Fralin is coming out with his own version of the P-90. If it's anything like his Strat pups, it will be truly awesome. Plus, he is a great guy. He called me himself when I ordered my pups just to make sure he knew what I was wanting to hear tone wise. I highly recommend him.
Dave