A few simple shortcuts to make working with fills and stokes a little easier. (In Photoshop's case, make that foreground and background).

X – This will toggle between fill and stoke at the foot of the tool pallette.

Shift-X This will transpose fill and stroke.

D - This will set an object back to its default white fill and black stroke.

, – This will fill and object with the last used fill.

. – This will fill an object with the last used gradient.

/ – This will clear an object of fill or stroke.

J - This will toggle between selecting object fill and text fill in the swatches pallette.