Aside from the obvious building blocks of single and double stroke rolls, what rudiments do you use the most and find indispensable?
Obviously a drummer needs single stroke (which I don't excel at) and double stroke rolls, but I can count on my fingers the number of times I've tried to use a triple stroke roll. I don't ever think in terms of counting four, five, six, seven or what-have-you stroke rolls, and I have to force myself to think in terms of flams, let alone all the possible variations like flamascues, flam paradiddle-diddles and pataflaflas (can't you go to jail for that?).
Paradiddles are where I live, and I probably over use them; to avoid that I sometimes practice in single strokes, but it's very difficult for me to resist the temptation to diddle somewhere. Unfortunately, to the majority of the English speaking world, diddling is tantamount to swindling, and for the coarser members of the race, a roll in the hay.
I though I had been taught all the rudiments when I was young, maybe sixteen in all, but apparently I rejected most of them. Imagine my despair at discovering things like the triple ratamacue. I can't even pronounce it.
http://en.wikipedia.org/wiki/Rudiment