I concur completely with all the pancake tips... especially about not being too large, and waiting for the bubbles to appear.
I make chocolate chip pancakes from scratch using a recipe I found online (although I don't measure the chips...). The trick to those is to use the mini chocolate chips, not the full sized ones. Like blueberries, the pancakes are "whiter" if you sprinkle the chips on the pancake while it's on the grill, but I like them really down in there so I just stir them in.
The trick to not having blue muffins is to reserve some of the flour while you're mixing the batter. Toss your blueberries into the reserved flour to coat them. Then add them last, folding and tossing gently until just mixed, then pour immediately into the muffin cups.
=)
Kk.