I've received various powder foundation samples from shops and friends (mostly from friends) and I've finally gotten around to testing them out properly.  At first I was reluctant to wear the samples in public as most of the shades don't match me well, but I figure that one day in the wrong foundation shade isn't going to affect me much.
Doltier Selective Powdery (a brand of Kanebo, made in Japan)
  *** Very natural finish, but only provides light coverage.  It seems average on oil-control, although I didn't pay that much attention.
Maybelline Angel Fit Pact (made in China)
  ** It fits seamlessly with my skin, but despite that the finish isn't quite as natural as Doltier.  It only provides light coverage.  The sample package is the most space-effective one though.  This foundation was supposedly developed for either the Japanese market or the Asian market, I don't remember which.
Ayura Superior Skin Pact SPF20, PA++ (made in Japan)
  * Not much coverage, and an average finish.  Not particularly natural, and normal about oil-control.
I've tried the above foundations for two days each. I rotated through twice.  The following foundations remain to be tested for this second round:
Revue Superior Stay Pact UV SPF 25, PA++ (a brand of Kanebo, made in Japan)
  * From what I recall, it was okay.  Revue foundations seem very popular here.
Paul & Joe Protective Dual Powder Foundation SPF 25, PA++  * very cute sample packaging, I was unimpressed on my first try, but the color was really off.
Dr. Ci:Labo Compact Foundation SPF 16 PA++
  * Good coverage and average finish.  I liked the fact that the sample package contains 3 colors for you to try.
Elixir Superieur Whitening Compact UV SPF 26, PA+++ (a brand of Shiseido, made in Japan, all seasons foundation)
  *** Good coverage, average finish, average oil-control.  I don't want to like this one, as I expect it is quite expensive.  Elixir skin care is on the costly side.
Maquillage Climax Lasting Powdery UV SP 25, PA++ (a brand of Shiseido, made in Japan, spring and summer foundation)
  *** Good coverage, average finish, average oil-control. Amusing name, eh?
Of course, I should just be using up my Inoui ID foundation instead of buying another one, but liquid foundation just takes too much time.