The shows I that I would be somewhat upset to miss an episode of are Heroes, Veronica Mars, Battlestar Galactica, and Good Eats.
But I also watch How I Met Your Mother, The Class, CSI: Miami (aka The Horatio Caine self-glorification hour), NCIS, House, American Idol (just started this season for no reason I can readily account for), My Name Is Earl, Scrubs, Smallville, The Daily Show with Jon Stewart, The Colbert Report, CSI (the original), The Dresden Files, and repeats of Star Trek and ST:TNG - all on a regular basis.
And I can add both Stargates, Eureka, and Doctor Who back to that list as soon as there are new episodes.
And I like to catch Kim Possible whenever I can, but I never seem to know when it is on.
And yes, I do use my DVR (and BT) a LOT. I don't schedule my life around ANY TV show.