At one point I managed my projects and tasks using a day planner stuffed with index cards. Since then, by way of a Treo 680 and later an iPhone, I've transitioned to digital, web/app based tools, such as Remember the Milk, gMail and Google Calendar.
Still, though, there always seem to be circumstances where the best solution is none other than a plain old stack of index cards, Hipster PDA style.
When I was stage managing an off-off broadway show, in the midst of tech or running around before the show, punching an item into a Remember the Milk list on the Treo just wasn't fast enough, but throwing a note on an index card was.
Similarly, I'm traveling abroad and have only a few hours before I need to leave on the airport.
It does me little good to put an item on a task list with a tickler alert reminder. There's just stuff that I have to do between now and then, so once again, back to the index cards.