I've always been a HUGE fan of UFO Robot Grendizer (Goldorak). Sadly most toys based on the series are either crazy expensive or impossible to find... like those gorgeous PVC action figures released a few years ago.
Here's an insane custom Splatterhouse action figure by Jin Saotome!
Here's Batman and Joker as Mr. Potato!
Sadly, Lego never got the G.I.Joe license. It was made by Kre-o.
Here's a crazy custom Lego Star Wars Star Destroyer!