well, aside from the fact that the first two aren't exactly still life subjects (they're more "an event frozen in time via flash" than something more mannered, arranged and considered) and the third is more of a "product shot" than a traditional still life...
First one - nicely sharp - good definition between the "ball of water", the hand and Dart and the black background. Generally I like it, but while I appreciate you kind of "get what you're given" with the balloon as it bursts, it's a shame that there wasn't just a tad more of it visible - we're talking maybe with the hand 1/2" further back out of the balloon, which would also have helped in making clear what the "bursting utensil" was without having to look in your hand for the flights of the dart..
Second one - pretty well exposed, but looking at the full size image on flickr, you're plane of focus is just slightly in front of the glass rather than running through the centre of the glass - this means that the item dropped into the liquid is not as obvious as it could be - perhaps not a problem with this item, but, say if it'd have been the (typical, done to death) Strawberry or Raspberry, then getting sharpness and definition on the fruit, and showing all the little micro-bubbles on it's surface would have been key. So, a good attempt, and scope for a cracker on the re-shoot.
Third one - Well... you've gone for a high-key background obviously, but in doing so, you've over-exposed things a bit, and if I'm not mistaken, you've missed the plane of focus again slightly. For setups like this, sticking the camera on a tripod, and using live-view is definitely your friend... I've often shot "tethered" with the camera attached and controlled by my laptop, allowing me a nice 17" screen to play with to ensure that the image is perfectly composed with respect to the desired DOF and so forth. Sorry, but for me, this one pretty much misses the mark.