In the Uncertain Principles Links Dump I find a pre-owned physics blog. (pre-owned: Not new, but new to me. It’s been refurbished, having been moved to new blogging software from an old program that didn’t work so well, so it appears newer than it actually is. So far as I know)
A lot of good physics, including several posts on basic concepts:
Basics: Vectors and Vector Addition
Significant figures what are they for and what do they have to do with uncertainty?
sig-fig-stickler
Oh, yeah. Say that three times fast.
Update: Basics: Fundamentals of Algebra, posted today