They look like small bruises or blocked pores. If they've been there a short time--and I don't see how you could overlook them for long--I would wait them out. If you get more, or these don't go away in a few weeks, you should show them to a doctor.
Take care.
Dr. Rockoff
Alright, it's my right leg and here's another image.
http://lib.store.yahoo.net/lib/mharp/leg2.jpg
I should add that these two spots are on the lower part of my left leg.