These apps seem particularly useful for remote workers. The list contains some essentials for general use and business, too. Stay tuned for a Blackberry and iPhone list as well!
Taskiller: Any computerized device needs the ability to kill a task. It's not just the Control-Alt-Delete of apps. Since Android's internal memory management decides when to shutdown an app, preemptively closing apps can free up memory and speed up performance on your mobile device.
Titanium Backup: After you've put so much hard work getting your phone to work for you - installing your favorite apps, deleting your not-so favorite, taking pictures, organizing contacts, etc. - it would be a real undertaking to try and restore it all without a backup. Titanium Backup stores all of your apps and settings on the phone's SD card, so be sure to occasionally backup the SD card in case your phone is lost, stolen or smashed to bits.
No Signal Alert: Has this ever happened to you? You're expecting a call, and look at your phone to check the time, only to find that you've lost service. Frustrating to say the least! So, it's essential to be alerted when you're in a calling dead zone.
Pro on the Go: Mobile expense tracking. Enter receipts manually or scan them with your phone's camera to create an "expense." The data gets uploaded to Pro on the Go's servers and then later you can download/import it in to Quickbooks.
Astrid: A simple and intuitive task manager/tracker, with some light hearted personality injected in the form of goofy reminders.
Opera Mini 5: Opera speeds up web browsing by compressing data before it gets to the phone (via Opera's servers), which then, in turn, saves on your mobile data usage.
Document Scanner: This app lets users make multi-page PDFs with their camera's phone. Perfect for sharing documents on the go!
Documents To Go: Documents to go provides a full suite for viewing and Editing Word, Excel, Power Point and PDF files. While I would normally endorse Google Docs, there surprisingly isn't a Google Docs for Android yet! GDocs, provides a third-party solution, but it ignores/discards your documents' formatting, which is - by all accounts - unacceptable.
Photoshop Mobile: Crop, resize, touchup, color correct/enhance. Perfect for blog administrators, and anyone else who's ever needed access to imaging tools from their phone.
Android VNC: Remotely access your desktop/laptop from your android device. Granted, your remote machine needs to be turned on and running a VNC server, which might be a bit intense for some users, but I've always found it's useful in a pinch. For more on VNC see the post entitled, "Holiday Travel: Stay Connected with Remote Access Tech"
These apps can keep you productive when you're out and about with only your smallest gadget. If you're an Android user, we'd really enjoy hearing which apps you've found invaluable!