My top ten on android are:
1) Flashlight, used more times than I would care to count
2) electrodroid, granted it's not the kind of thing everyone will use but if you work with electronics it is amazingly well put together and informative.
3) Tesco groceries, sad as it is, I do my tesco shopping in the bath
4) The ebay app, it works well, it's fast and spot on in every way.
5) ES file explorer is really handy, with its own media players it does everything I need to access the files stored on my SD card.
6) After that you can never have to much minecraft so the minecraft game is next on my list.
7) Google sky maps, amazing to look at the stars, even better to know that it's actually a planet you are looking at.
8) Xconstruct is a great game, I paid for the full version, sadly they dont update it with new levels as much as they did in the past.
9) Opera Mini, so much better then the standard browser.
10) Advanced task killer, because WHY oh WHY do all those apps keep running after you close them, having one button to kill it all is great at saving battery.