I've had an Android phone for about three months ish now, and whilst it hasn't quite revolutionized my life, it has made gaming on the go somewhat easier.
Here are the apps that turn my pocket into a gaming repository:
Internet Browser. Often overlooked, but the power of todays' mobile browsers is astounding. I read and contribute to forums exclusively from my phone nowadabys, and catch up on all my gaming related news as well.
Adobe PDF Reader. This app just keeps getting better. When I first got my phone, the Adobe app was just about acceptable for reading an 80 page copy of Mage Noir, with a lag as it uploaded. Now it has been updated twice and is much faster, easier to use and better presented. A must for the books you don't want to carry around with you.
NWoDice. A World of Darkness dice roller that is intuitive, quick and well presented. It covers off 8, 9 and10 again and chance die really well.
Dice Bag. A dice roller app. The jury's out on this one. It could be really spiffy, and does present a lot of options, but is kind of clunky to use. It does allow you to roll a full range of dice with modifiers and multiples, and to create your own dice (d11, anybody?).
RpgTracker. A nice little app that allows you to monitor any renewable resource you can think of: Health / Hit Points, magic points, willpower, blood pools, essence, healing surges etc. You name a character, create each stat, assign a max and current score, and then track from there. It even includes a formula field for stats that replenish over time, although I've not figured that one out yet.
Name Generator. This app will randomly generate a number of names for you based on which gender and nationality you select. Apparently it knows the most popular first and second names for each country on the list and works from that. Even includes ancient Greek and Roman names.
Pathfinder Spell Compendium. Allows you to drill down to the full spell text by class and level, or to search on the spell name. Very quick.
Blogger. What I'm using to write this right now. It's not advanced enough to edit posts you've created on a PC, but is very versatile nonetheless. And once you've published a post using the app, you can edit it at a PC as normal.