As also found in the official Google Android Market:

This application is a call minutes, sms, mms and data usage meter to monitor your credit usage. Never exceed your quota again!

Supporters unlock: free times/contacts/groups; widget; usage log; greater configuration of plan inclusions + more. A free 5 day trial is offered.

Please report bugs!

Please visit http://creditusage.matthewwardrop.info for more information.

A simple App to backup and restore SMS Messages, useful when doing a factory reset or installing custom ROMs. The backup is stored in /sdcard/SMSBackupRestore folder.

Please report any problems you are having with the App on my site in the comments section or email me with the details as I cannot respond to problems in the market.

http://android.riteshsahu.com/apps/sms-backup-restore

This auto responder app allows you autoreply via sms to any incoming calls or sms during a specified time range that you schedule.

Features:
custom sms reply message
target specific contacts
repeat on weekly schedule

Works on Droid HTC Eris HTC Nexus One HTC Incredible plus more
Supports Android 2.0+ & Froyo
48-Hour Trial

Don't miss out...send yourself a message instead!
Similar to Missed Call Messenger, this app will send you a message when a calendar event is near.

This app is extremely customizable with many options to suit your needs and style. Updates and new features are frequent.

Don't miss what matters most, get notified!
This application will display a popup notification window when certain phone/app events occur.

This app is extremely customizable with many options. Updates and new features are frequently added.

Use your front camera as a mirror.

The Best Parental Control,Spy and Phone Backup/security app for Android.

• SMS & MMS Forwarding
• Call Notification Forwarding
• Call Recording & Forwarding
• Backup(SMS, Call Log, Contacts e.t.c)
• Phone Locator/Tracking/Security/SIM Change Alert
• Parental Control (Kid Monitoring & Tracking)
• Secret Monitoring of Text Messages,Calls & Location

100% stealth SPY version is also available as Total SMS Control-SPY

TTSNotifier: A speech notifier for android - Incoming calls, SMS (person and/or body), Wifi connect/disconnect, special ringtone support, user defined texts and more...

Easily access the 5 most important people in your address book with Quick 5!

Fast Translator

is a free translator with 37 languages supported including the most used languages , you can easily translate any language.

Send sms,mail,facebook, your translated messages in any language, (pro only)

Send a Sms in only one click !

Watchlion helps you to keep some contacts private. All SMS message and call log will hide from the android system.

- Convert Unicode text to VIQR text.
- Easy to send Vietnamese SMS, Email...
- Save your money by sending VIQR SMS.
- One click copy to clipboard.
- Support portrait and landscape screen.
- Totally free.

When you are in trouble press the red panic button! You just have to set a panic number and the phone will send a sms which contains a link to Google Maps with your fine GPS based or coarse GSM based coordinates.

Have you ever been trying to meet friends in a large public space, but been unable to find each other? I created GPS Share for just such a scenario.

phoneklone brings your phone to the Internet. All your photos, text messages, location and settings all available online in an easy to use, personalized portal at www.phoneklone.com.

Features:

-What you love to do on your phone, instantly online. Photos and text messages are uploaded as they are received so you never have to worry about sharing and uploading again!
-Lost your phone? Use phoneklone to find it!
-All your text messages are available online, instantly!

A simple, clean and easy to use SMS Scheduler.
Pick a time and date, a recipient and a message, and it will be automatically sent for you at the specified time.
You can also specify a repeat option: daily, weekly, monthly or yearly.

Mobile Spam Agent is a smart sms filter that uses machine learning techniques to analyze and detect text spam.

Open-source SMS filter application with wildcard and regular expression support

Send and receive 3D visual messages for free. Create a 3D card, photo card or 3D animated musical card and send it as an SMS, Email or post it on Facebook. Start from pre-bundled card or download more from CardzStore. Personalize it by customizing the text, background and interacting in 3D to get the desired view of the card. Turn your photo into a 3D card by clicking a picture and using it as card background. Once you are done, just send it. Track your cards, do a visual chat on Inbox.