1) Get out Heroes Unlimited. Ignoring the randomness of the random power chart, make a Superhero.
2) Get the RIFTS Conversion book and convert the Superhero's stats into RIFTS.
3) Start loading him down with RIFTS gear, like getting him a SAMAS or Glitterboy.
The ultimate Rifts character at first level though was made on the Palladium Books forum and had tens of thousands of melee attacks, could launch all of them in under four seconds, and was totally book legal.
AnubisXy posted it months ago, and he didn't even save it. It did involve an Octoman with added bio-magic limbs, rings with magic adrenal rush and fleet feet, and Muay Thai's Lightning Kata, with a few other nasty things I forget. Anubis says he's going to try and reconstruct it once he gets all his books back.
[Edit] Oh yeah, Battle Fury blades too.
I always wanted to "3.5" Rifts for better play but never did.
Juicers I remember were powerful. Beyond that... I played only once but bought about a dozen books to use then the group decided they didn't want to try something other than DnD. Aw well.... it's just money (I can say that then since I had unlimited OT and nearly no bills)
By craziest combo, tho, are you talking about PC combos?