I'm a huge fan of the Sign Of The Times multi-player autos Upper Deck put out back in the day. They feature on-card signatures, are beautifully designed, and allow a player collector such as myself to add John Hancocks from guys I don't collect but like to watch without having to chase non-PC stuff and feel like I'm spreading myself too thin. It also doesn't hurt that Matt Kemp is prominently featured in the SOTT sets.
My latest pickup drives home those points as I landed this gorgeous SOTT Triple from 2008 SP Authentic Baseball, numbered 06/50.