So you are running a Nexus One with Android 2.2?
1. This app allows messaging over bluetooth to another Android handset: http://www.androidpit.com/en/android/market/apps/app/com.androidotcom.bluetchat/Bluetooth-Messenger
2. Try this app for a to-do list: http://www.androidpit.com/en/android/market/apps/app/com.myzu.todolist/To-Do-List
3. I believe that every Android phone comes with an audio recorder built-in as part of the operating system, but there are apps that you can download which will do it as well, and that may work better for you. Maybe give this one a try and see if it works out for you: http://www.androidpit.com/en/android/market/apps/app/com.samalyse.free.tapemachine/TapeMachine-Free-Recorder
4. These are a cool games/ recommended apps threads:http://www.androidpit.com/en/android/forum/thread/394899/Your-Best-Apphttp://www.androidpit.com/en/android/forum/thread/398529/most-used-app
5. When you say that you want to protect your phone from hackers, do you mean from people hijacking it over the internet or something? I haven't heard of that happening to anyone yet, but there have been some apps which many people thought may be viruses/malware. This is an Android anti-virus, but it is hard to say whether it does a good job, because there aren't very many, if any, Android viruses running around ruining peoples' phones.
If you are also concerned about your phone being stolen, I recommend adding a pattern lock code onto your Android phone. This can be done in settings, security & location, screen unlock pattern.
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