A few essential apps for those more technically minded Android users out there. If you know of others that should be in here let me know in the comments.
This one is almost a no-brainer. Everyone who knows Android is Linux underneath (and who knows Linux) normally heads for a command line to check things out right off the bat. You can get access via ADB, but having direct access right on the device is killer. This app gives you access to the command shell built into the device.
Market link: Android Terminal Emulator
ConnectBot is an SSH client application for your phone. It’s a fantastic application for quick access to remote systems. If you’re on a device without a physical keyboard it’s not quite as slick to use (I wouldn’t recommend trying to use vi on a remote system from a Samsung Galaxy for instance), but for quick tasks it can be fantastically convenient.
Market link: ConnectBot
Advanced Task Killer
This seems to be a pretty consistent tool in most advanced user’s toolboxes. Android apps can keep running in the background. Most of the ones that do give you good ways to control when they run, and the OS itself does a generally good job of managing them. But if you tend to poke around with lots of apps and try out all the different tools you hear about you’re bound to run across one or two that misbehave every once in a while. When you do, Advanced Task Killer can help you figure out what’s going on and set things right again.
Market link: Advanced Task Killer
Astro File Manager
This is the free version of a file manager application. There’s a paid version that includes a ton of additional features, but so far I’ve stuck with the free version. Nice interface for browsing around and seeing what files are on your device. Includes built in viewers that generally handle text and image files well.
Market link: Astro File Manager
Dropbox is a free service that lets you store files online and sync them between systems. If you don’t already have an account and want to try it out please sign up using this affiliate link (I get credit for the signup and get some free space on Dropbox if you do). They have an Android application that allows viewing, downloading, or uploading. Together with an application like Astro you can upload arbitrary files from your phone to Dropbox as well. From within Dropbox use upload from the menu, and then select any file and use Astro to complete the action.
Market link: Dropbox
Scripting Layer for Android
An app that allows for accessing native Android functions from multiple scripting languages. Once you install SL4A you can use it to pull down interpreters. A bunch are available, like Unix shell, Python, Perl, Ruby, and others. Then you can run scripts in those languages that tie into Android specific functions. SL4A is not available in the Marketplace however, so use the info on the Google Project page to download the apk directly. If you’re on an AT&T device like the Samsung Captivate and haven’t hacked it to allow direct third party installs you’ll have to load the apk files using ADB. As of right now, it seems you need to download the core SL4A app and then separate downloader shims for the different interpreters. The base sl4a seems to only have shell installed by default. But once you install something like python_for_android_r1.apk and click install within that app you’ll get Python support in sl4a.