IPhone – What Are The Best iPhone apps to keep a toddler amused in an ’emergency’

VLC is by far the best.

Fast, extensible, and versatile. You can play just about any format video, Video_TS file, remote disks, remote streams, even pipe the output of a command into it to play. Can you say on the fly video manipulation? That's VLC.

Not to mention the main selling point, it's free.

Quicktime? Slow. Plugins? Hokey. Alternatives? Either not very "native" or buggy, slow, and prone to crashing. There is not one thing I have been unable to play with VLC that I had to use something else.

Okay, one thing. The MKV support on it is a bit of a pain. Try seeking with a 4GB MKV file.

If you want to print pictures and photos, you can use Epson iPrint (there are similar apps from other printer manufacturers, e.g. Canon iEPP, HP iPrint Photo 2.0, Kodak Pic Flick or Lexmark LexPrint). For printing PDFs or other documents, the already mentioned "print n share", "Print Bureau" (both from eurosmartz) or Air Sharing Pro from Avatron could be useful.