Email and calendar
Perhaps the most common tool for managing business-based email on Google's Android OS is Nitrodesk's $20 Exchange for Android (formerly called Touchdown). The app allows for secure connections between your Android smartphone and your company's Microsoft Exchange email server. It features a wide range of security options, including data encryption and remote wiping of corporate email data. The program can also be mass-deployed by administrators, making it one of the most IT-friendly solutions available.
Email aside, a service called CompanionLink offers a range of methods for synchronizing your contacts, calendar, tasks, and notes between a PC and your Android smartphone. CompanionLink works with Microsoft Outlook, IBM Lotus Notes, Novell GroupWise, and a handful of other common desktop utilities. It can sync your data via Wi-Fi, a direct USB connection, or over the Internet by linking up directly to your Google account. CompanionLink costs $40 for the Outlook edition and $70 for the Lotus Notes or GroupWise version. Note that the Google sync option will send larger businesses' IT groups into fits, as it circumvents their security controls by forwarding email and other data to the unsecured Google service; for them, CompanionLink offers a secure cloud-based forwarding server product instead for $10 per user per month.
If your Outlook calendar is all you need to keep in sync, Google's own free Calendar Sync program may be the tool for you. Google Calendar Sync runs on your PC -- but not Mac -- and, as its name suggests, provides an ongoing two-way sync between your Outlook calendar and your Google Calendar (which is by default linked to your Android smartphone). The program is free to download and use. Like CompanionLink, though, its use will cause security conniptions at many organizations.
Regardless of what synchronization tool you do or don't use, you may want an Android widget to provide easy access to your calendar from your smartphone's home screen. François Delandes' €1.50 Pure Calendar widget is a highly customizable app that puts your upcoming events and appointments right at your fingertips. You can select from different sizes and configure the widget's look to your liking. You can also actively scroll through your calendar within the widget if you use it with an advanced launcher like ADW or LauncherPro.
Notes and lists
Catch.com's free Catch Notes is a great tool for on-the-go note-taking and organization. Catch provides an easy-to-use interface for jotting down messages and reminders: You can tap out a note on your smartphone's keyboard, speak a note via Android's built-in voice recognition, record an audio note to be saved for future playback, or capture a visual note via your smartphone's camera. All of your notes are saved into the app and can be synced to the Web and other devices using your Google account or an account with Catch.com (which costs $5 per month).
A popular note-taking alternative is Evernote, which performs most of the same functions as Catch but requires an Evernote-specific account to function (free for individuals and $5 per user per month for companies). By contrast, an account on Catch is needed only if you want to enable syncing. Personally, I prefer the Catch interface, but both apps are excellent and fairly well matched in their capabilities.
Want to create a quick note to yourself without all the bells and whistles? Try Google's Voice Actions for Android, available free for any smartphone running Android 2.2 or higher. With Voice Actions, you can press and hold your smartphone's Search button and speak the words "note to self" followed by your message. Your smartphone will instantly transcribe the message and send it to you in an email.
If you're looking to make more traditional lists, Todoroo's Astrid Task/Todo List is a fine way to get the job done. Available as a free download, Astrid lets you create multiple to-do lists and check off tasks as you complete them. You can set individual task reminders, sync your tasks with Google Tasks, and automatically create new Google Calendar events for items as you add them. An optional $4 Power Pack gives you widgets, voice reminders, and other features.
Remember the Milk is another popular and full-featured list-making utility for Android. At its current cost, however -- $25 per year -- I can't recommend it; that price simply isn't competitive with other comparable options available for free or for one-time fees.
DDH Software's $10 HanDBase Database Manager gives you the ability to create and edit work-oriented databases from your smartphone screen.
Glen Hughes's $3 Remote DB app enables SQL access from your Android device. It supports Microsoft SQL Server, MySQL, PostgreSQL, and Sybase database environments.