I know I've certainly had this problem. Theirs the obvious choice of "tank, infantry, walker, APC...." But when you want something off the wall you can never think of anything!
But I've found this:http://www.thesurrealist.co.uk/priorart.cgi?ref=
The ultimate idea generator. Not all are good, but some are.
>It's a glass bead that can speak twelve languages! It smells of flowers and explodes when dropped.
>It's a pot plant that displays pornography! It doesn't distract you from your work.
>It's a newly-discovered breed of fish! It hasn't gone on any murderous rampages yet!
>It's like a normal bar of soap, but it hovers.
>It's a genetically-modified sheep that tells you when people are lying, communicates with wireless devices and is built and maintained by tiny nano-robots.
>It's a car! It displays pornography!
>It's a deck of cards that comes with a variety of coloured fascias and gets +2 to kill undead.
>It's a robotic dog that hovers and is bigger on the inside than the outside. [this is seriously quite a cool idea]
>It's like a normal pudding, but it can move faster than the speed of light.
>It's an explosive device that's water-absorbent!
The incredibly non-useful:
>It's a housebrick that catches fire very easily!
>It's like a normal bubble-car, but it emits harmful gases.
>It's a WAP device that probably won't work! It can be taken apart and reassembled in thirty seconds and fetches help in the event of an emergency.
>It's a penknife! It emits harmful gases!
>It's a waffle iron that's two inches tall!
>It's a pair of sunglasses! It is made entirely of wood!
>It's a screwdriver that hovers three feet from the ground! It wears a waistcoat and tie and is inflammable.
>It's an electric drill that dissolves in water! It may cause drowsiness and is made of glass.
>It's a suppository! It hums incessantly!