Mile
Zero

My love for Locale aside, what else is good on Android? Inquiring minds want to know.

• K-9: I am, apparently, a total weirdo in that I don't use G-Mail. I have an account, of course, because it comes with the whole Android developer thing, but I pretty much only use it when Google requires it. Unfortunately, the POP/IMAP client that ships with devices--even up to and including version 2.1--is awful. It forgets which messages I've read, doesn't easily allow batch operations, and decides randomly not to connect. K-9 started as a fork of that client, but it's reached the point where it's the only reasonable choice for handling non-Gmail on Android. There are still some things I'd like to see added (text-selection, recover from trash), but it also has touches of brilliance (check out the swipe-to-multi-select list mechanic).
• Touiteur: There are lots of Twitter clients on Android, and for the most part it's a matter of personal preference which you use. Seesmic is great, but it keeps asking me which account I want to use even though I've only got the one. Lately I've been using Touiteur instead, for a few reasons: I dig the pull-down windowshade for updates, the UI for jumping out to links is better, and it's super-speedy. Also, the name cracks me up. Like all Android clients, of course, Touiteur gracefully handles checking for messages and mentions in the background via the notification bar, and it makes itself available to the "share" menu for URL-shortening right from the browser.
• Ringdroid: One of the main goals for Android is that it's not tied down to a computer. Everything's either in the cloud, or it's meant to be self-sufficient. Sometimes this can be frustrating (I'd love to have Outlook sync included), but for the most part it's liberating. Take Ringdroid, for example: it's a basic WAV/MP3 editor that you can use to edit and set system sounds directly on the device. I don't use it often, but if I decide to nerd out on the bus and set my notification tone to a Star Trek communicator clip I found online, Ringdroid makes it possible (and yet no less shameful).
• Text Edit: Every platform needs a Notepad.exe equivalent. Unfortunately, most of the note-taking programs for Android keep their data siloed in a private database, which defeats the point of having that SD card filesystem available. Text Edit actually opens and saves files, which makes it tremendously helpful for someone like me who'd actually like to get some work done in a standard format every now and then.
• Smart Keyboard Pro: You can replace almost anything on an Android phone if you don't like the default, and I don't much care for the built-in soft keyboard. Specifically, I hate the way it keeps all the good punctuation hidden away from me. Smart Keyboard offers good foreign language support, swipe gestures (one of the better bits from Windows Mobile), multiple skins, and Blackberry-like autotext shortcuts. But most importantly, it puts all the punctuation on the keyboard as a long-press of individual letters, so I don't have to hunt for question marks or semi-colons anymore.
• Replica Island: There aren't a lot of great games on Android, but Replica Island (which started as a tech demo for the platform) is a well-done little platformer, and it's free.

The interesting thing about making a list like this is, for me, was that I realized how little use most of the native software on the device actually sees. 95% of my time on a smartphone is spent in three places: e-mail, Twitter, and the browser. That's not to say that I don't use other applications--that I don't find them phenomenally helpful, or that I wouldn't miss them if they were gone--only to say that as a matter of routine, those three are what matter most. Everything else is gravy.

(Well, almost everything. When people ask me about whether they should get a smartphone, the first thing I tell them is that Maps will change. Their. Lives. Because it absolutely does. I spend relatively little time in Maps, but it's probably the most valuable application on the phone.)