I'm thinking of the bottle-capper that came with my original kit setup. Useless as all get out because I only use Coopers 750ml PETs!
Probably the most useful thing I have is my sugar measurer, followed by some 'diet' kitchen scales with increments of 5g up to 500g [$6 from Big W], some dual-beam scales that go in increments of 0.01 of a gram up to 10 grams [great for hops!], and my LED torch which I use to check clarity of brews in the fermenter and let me take proper temp readings in below-par light.
One of the 'grooviest' things I have at the moment is a 5L demijohn - I carbonate it up with 30~35g of dextrose, and bust it out at a party every now and then.