Let's say you need 4 random elements fast. (What will be the 5 main monsters in this dungeon? Who are the most important NPCs in the town? etc.) You're either prepping fast or are trying to do this during play.
You could roll 4 times, or draw 4 standard-deck playing cards with things you wrote on them in sharpie.
-Here's an advantage to using the cards instead of a die roll:
Since there are suits and numbers, if you use them, cards not only can give you results, they can automatically create relationships or connections between the results.
For example: You can assume any 2 cards with matching suits are on the same "side"--part of the same faction or the same race, etc. and any 2 cards with matching numbers are on opposite sides--enemies, vying for the same goal, etc.
This also makes it easy to draw additional cards and add them to whatever's already going on--any new card has a chance of being related, but not an overwhelming one.
-Here's another advantage: The relative numerical values on the cards you pick can be used to establish things like which monster the PCs meet first, or the status or power levels of a handful of NPCs relative to each other. Like if you get ace 4 7 king you know the Ace is the mook, the king is the boss, and the 4 shows up before the 7.
(Note this isn't as true with tarot cards--unless you know the tarot well, the various major arcana--half the deck--have no obvious connections between them.)
Drawback: This method will only create connections that were waiting there when you wrote the cards to begin with. i.e. the 10 of clubs and the 9 of diamonds will never be automatically connected using this method. Obviously you could create your own connection, but this is the kind of random generator (Simple, Complete) where the point is it does all the work itself.