Overlook Fing is a great network scanning tool if you want to see what connected to you home network, or any wifi network you are on at the time.
I use VNC viewer occasionally
I use Syncness to backup my photos and a few other folders to my network drive automatically.
CamScanner is very useful, it uses your camera to turn a document into a pdf, does multi page as well.
Ringdroid lets you select a chunk out of a music file and use it as a ring/text tone
I like tunein radio for internet radio.
I have an app that plays video files from my phone to my TV but can't remember what its called, just looked and it could be 1 of 3
I like Touchdown for my email, works with exchange servers but I use it for push windows live email, its a bit expensive as far as android apps go but it is the best I tried.
I use Handcent as well for texts but use the twitter app by twitter anb the facebook app and facebook messenger app by facebook. The Facebook messenger app is very good. Gives you push notifications of new messages and all you messages are stored in facebook still.
Audiomanager lets me set audio profiles for home, work, quiet, silent etc
I think one of my favourite apps is tasker, it lets you write your own automation tasks. I wrote ones to turn off wifi when connected to my car kit to save battery and turn off bluetooth when connected to my home wifi. You can make it do all sorts of simple or complicated things. You can write tasks based on gps location or which wifi you are connected to or by time of day. Rhonda's phone puts itself on quiet at night and back to normal volumes in the morning. My eldest sons phone has task to switch itself to silent at school time to stop him getting in trouble.