CPU-Z: This app provides all the information about your device, like model number, manufacturer, hardware, ram and storage details.
AVG Antivirus Security: Free Anti-Virus security from AVG, to protect your phone from viruses.
App Dialer: If you have loads of apps on your device, app dialer helps you identify them quickly by typing the first few letters.
Apps 2 SD: Move all your apps to SD card when you think your device memory is low.
Backgrounds HD Wallpapers: This app has lots of HD wallpapers to decorate your phones home screen.
CamScanner -Phone PDF Creator: Helps you scan your documents, business cards and stores as a PDF.
ES File Explorer File Manager: If you are not happy with the default file manager you could try this.
Google Finance: Great finance app to monitor you stocks, also allows you to create portfolios.
RAR for Android: Unzip the rar files you receive in your email.
Drippler: This app will list out all the new apps that are available in the play store with comments.