1) MyBackup Pro With this app you can create backups of all the important data on your phone to your SD Card or RerWare's online secure servers. Then you can restore that data to any phone that MyBackup Pro supports, regardless of platform. Paid: $4.99.
2) CacheMate for Root Users CacheMate allows you to clear the cache from all your apps with a single click. You can even set it to automatically clear the cache according to a schedule: anywhere from once an hour to once every few days. Requires Root. Paid: $1.
3) Memory Booster Keep your Android phone running at its fastest with this app. Memory Booster optimizes our phone's memory by recovering memory leaks, flushing temporary libraries and defragmenting your phone's memory. Paid: $2.95.
4) Easytether Pro Looking for a solution to turn your Android phone into a mobile modem? Easytether Pro lets you tether your phone to Windows, Mac OS X, Ubuntu Linux, PS3, Wii and Xbox 360 devices with no tether fees and without requiring root. An easy-to-use wizard guides you through the tethering process. Paid: $9.99.
5) Beautiful Widgets Not content with the widgets, themes and skins that came with your Android device? This app is what you need. It features hundreds of downloadable skins. Paid: $2.82.
6) WolframAlpha Access WolframAlpha's computational knowledge engine from your phone with this app. Also available for free via the WolframAlpha Web site, the app calculates the answers to complex mathematic and scientific problems in an instant. The app version adds a keyboard with all manner of mathematic and scientific symbols to make entering queries a snap. Paid: $1.99.
7) Anti-Virus Pro Concerned about malware, viruses and SMS spam? Anti-Virus Pro is a comprehensive security suite for Android that can scan apps, files, settings and media in real time. Paid: $9.99.
8) ASTRO File Manager This app might just be essential. It's a full-featured file manager that lets you view and manage the files on your Droid without having to plug it into your computer. You can even use it to backup your Android apps to your SD card. Paid: $2.99.
9) Locale Locale lets you manage your phone's settings based on predefined criteria. For instance, you can set situations like "at school" or "in court" and set the phone to change its volume setting to vibrate when in those situations. You can set automated controls based on battery, location, contact, orientation and time. The phone settings you can alter based on these situations include: Bluetooth, brightness, ring tone, screen timeout, volume, wallpaper or Wi-Fi. Paid: $9.99.
10) NewsRob Pro This is an excellent, plain but functional Google Reader client with built-in syncing for off-line reading. Paid: $5.83.
11) RepliGo Reader A PDF reader that can be used to view Gmail PDF attachments, online PDF documents or PDF files saved to your media card. It features a reading view that reformats pages into a single column, and offers support for embedded fonts, PDF bookmarks and text search. Paid: $4.95.
12) JuiceDefender Ultimate Is the battery on your Android phone consistently running on empty? JuiceDefender can help you extend it! The app intelligently manages your mobile connectivity and other battery-sensitive components to ensure your phone runs as efficiently as possible. For example, the default mode switches your phone from battery-intensive 3G mode to the less-draining 2G mode when you're not actually using the phone, and it turns of the Wi-Fi radio if the charge goes below a certain level. The Advanced Mode allows you to tune the app's triggers based on your individual needs. Paid: $4.92.
13) NESoid This Nintendo Entertainment System (NES) emulator allows you to play every NES game ever made right on your Android phone. You'll have to take responsibility for the legality of your ROMs. Paid: $3.98.
14) Hullomail Wish you could get visual voicemail on your Android phone? Hullomail has you covered. This app allows you to manage, send, receive and share voicemail from your phone. You can even check your voicemail from the Web. Paid: $6.99 per year.
15) Tasker Want more fine-grained control over your Android phone? This app allows you to automate tasks and set contextual rules that make your phone behave exactly as you want it to, from automatically going into silent mode when you enter a movie theater to playing a random song from your music collection to wake you up in the morning. The options for a power user are staggering. Paid: $6.50.
16) Sketchbook Mobile Keep a sketchbook with you wherever you go with this full-featured app from CAD specialist Autodesk. Sketchbook Pro is a professional-grade paint and drawing application with a whole host of tools. It's great for graphic designers on the go. Paid: $0.99.
17) SetCPU for Root Users This tool allows you to change CPU settings, including overclocking and underclocking, on a rooted Motorola Droid, Nexus One, G1, G2, Samsung Galaxy S, myTouch 4G, Motorola Xoom, or one of many other devices, allowing you to increase performance or save battery life. You can even set up profiles to change settings conditionally. For instance, you can set the phone to change profiles if the charge falls below a certain point or the phone's temperature gets too high. Paid: $1.99.