Agreed.
A small lift (=/>2") for the suspension to get the frame and body a little farther up off the ground,
Real gas tank and front skid plates to protect your fuel source and front diff (AFTERMARKET4X4.com has great fitting ones made out of 10 gauge steel that bolt right on)
http://cgi.ebay.com/ebaymotors/Tracker-Sidekick-INDESTRUCTABLE-Gas-Tank-Skid-Plate-NEW-/300565901559?pt=Motors_Car_Truck_Parts_Accessories&hash=item45fb1fb0f7#ht_1059wt_962Transfer case gears for a little more high end and low range mechanical advantage to the tires
Later on an ARB air locker for the rear end of your truck. Push a button and the rear is
locked like a spool, pull out onto the road to drive home, flip the switch and your back to a normal driving/handling rear differential. You'll go farther with a locked rear end in the woods and trail.
IF you can save the bucks for awhile.... later on down the road, invest in an OME tuned suspension system (Struts, shocks and spring set) to really provide you a top of the line suspension for the road and trail,
I think those additions will make your truck about as trail capable as it will get without significant suspension upgrades like straight axle conversions or buying 5.38 or 5.62 ring and pinion gears from earlier model Track/Kicks and having them installed into your diffs to pull larger diameter tires effectively.
As indicated above by Samuraidan, you could probably sell your 5.12 gears to other forum members looking to upgrade their gears to off-set the cost of buying the 5.38s or 5.62 gears for yours. You would have to modify them for the 26 spline axles your truck has, but it is doable and the increase in torque generated for turning a taller tire would be quite noticeable.
But seriously, these little trucks are quite impressive right out of the box. Just drive wisely, look
before you leap, and have fun. These trucks are addictions waiting to happen.