Essential smartphone medical apps

What are the true "essential" apps (or applications) for medical students and residents? (by the time you're an attending, you shouldn't be relying on a smartphone, right?)

In some ways, I'm tempted to say, here are the essential medical software you need to survive:

1. Epocrates
2. Internet-enabled web browser (this way, you can look everything else up)

Of course, that would be the simple way of viewing things. You can't live without:

• Medical calculators (which are often included within Epocrates)
• If you can afford it, I would highly recommend UpToDate (web-based access is sufficient)
  
• the rest of this list is highly dependent on your smartphone operating system.

Medical references can be invaluable. I would recommend things like the Merck Manual, the 5 Minute Clinical Consult, etc. However, if you have access to UpToDate online, then you won't need most of those.

Finally, the list of "essentials" really depends on your level of training. If you're a 3rd year medical student on a clinical rotation, your smartphone needs are different from an intern who's expected to stay very organized and keep up with a million tasks. Your smartphone needs will evolve over time and you'll find that certain apps lose importance as you memorize one thing and rely on another. For instance, some people love the Sanford Guide while other people don't know how to use it. So my list of "essentials" is relatively short because the Internet becomes the ultimate "essential."