I just maxed out the feeble internal memory of my dersire 2.1. Not including apps that directly effect the functionality of the phone (sound management, sms, ebay ect.), this is what I have, if anyone knows any better or other apps that would fit within these titles I'd like to hear it 
:
Network:
Wifi Analyser: great app to see available networks and their signal strengths.
Wardrive: Awesome app that detects open wifi points and maps them onto a google map. Lets you easily see where you can steal internet.
Speed Test: Shows the quality and speed of your internet connection.
GPS Test: Shows how many satelites the device can see, their signal strength and estimated accuracy. Sunrise/sunset, time, speed ect also shown.
PrinterShare: print directly from your phone over the internet to any printer that has prog installed. Or directly to wireless printers.
Tools:
Metal Detector: Uses the manetic sensors to detect ferrous metals. Not sure of its usefulness but its fun to show people.
Smart Measure: Measures distance to the base of any object (as long as its on level ground).
Bubble: A simple spirit level, great and gets used quite a lot.
Realcalc: A great scientific calculator.
Barcode Scanner: Being in Australia, this is pretty pointless but its there just incase.
Compass: Good flat compass, used it for aligning tv aerial.
Smart Compass: Flat compass not as good as the above, however it also enables you to view an object with the camera and see its bearing and magnetic field quality, works well.
Unit Converter: converts any unit imaginable, want to convert fathoms to microns this will do it.
decibel: A sound meter which probably doesnt work at all.
DCE Chempad: Calculated the molecular weight of whatever molecule you draw, then can search chemspider for its other properties.
Google:
Sky Maps: view the map of the stars using the orientation sensor.
Maps: Just google maps, infinately useful as we all know.
Goggles: Use it for them square bar code thingys, doesnt seem to be useful for anything else. Not very good at finding like images.
Earth: Not sure if Maps need this to give sat data? but I never open this, Maps is much better.
Google Translate: Would be really good if I actually needed to know another language, but as is I just annoy people by using it to talk for me using text to speech.
Games:
Robo Defence: was kinda OK tower defence game, gets boring fast though even though you can upgrade your turrets I'm just not interested.
Fishin 2 Go: Pretty nice fishing game.
Alchemy: Combine elements to create new ones, very simple but good time waster.
Glyder 2: Uses orientation sensors to cortol a chick with wings around a map. Fun to explore and pickup things. Nice game.
Video Strip Poker: get a video of a couple nice girls removing a consecutive pieces of clothing for every $100 you take from her. Yeh its OK for what it is.
AnDrawing: good drawing program. Best I could find, ;latest update has shapes (square, circle ect.) though still doesnt have straight lines.
Surveillance:
Noise Alert: once the noise level reaches a set threshold it rings a preset phone number so you can tap into whatever the noise is.
OmniEye: Allows you to remotely view your PC webcam through your phone.
SECuRET Spycam: A motion detecting video/stil camera. When it detects motion it either takes video or a pre set amount of images and either emails them or saves them to SD.
Sca Lite: hides the viewfinder of your camera and prevents shutter noise, so you can discretely take photos.
Scanner radio: Recieves many worldwide emergency (police/fire/ambulance) radio signals, tap into most signals even here in Australia.
Seismo: A seismograph, not real useful but as it does nothing when it detects vibration. Only traces a line of it.
:Network:
Wifi Analyser: great app to see available networks and their signal strengths.
Wardrive: Awesome app that detects open wifi points and maps them onto a google map. Lets you easily see where you can steal internet.
Speed Test: Shows the quality and speed of your internet connection.
GPS Test: Shows how many satelites the device can see, their signal strength and estimated accuracy. Sunrise/sunset, time, speed ect also shown.
PrinterShare: print directly from your phone over the internet to any printer that has prog installed. Or directly to wireless printers.
Tools:
Metal Detector: Uses the manetic sensors to detect ferrous metals. Not sure of its usefulness but its fun to show people.
Smart Measure: Measures distance to the base of any object (as long as its on level ground).
Bubble: A simple spirit level, great and gets used quite a lot.
Realcalc: A great scientific calculator.
Barcode Scanner: Being in Australia, this is pretty pointless but its there just incase.
Compass: Good flat compass, used it for aligning tv aerial.
Smart Compass: Flat compass not as good as the above, however it also enables you to view an object with the camera and see its bearing and magnetic field quality, works well.
Unit Converter: converts any unit imaginable, want to convert fathoms to microns this will do it.
decibel: A sound meter which probably doesnt work at all.
DCE Chempad: Calculated the molecular weight of whatever molecule you draw, then can search chemspider for its other properties.
Google:
Sky Maps: view the map of the stars using the orientation sensor.
Maps: Just google maps, infinately useful as we all know.
Goggles: Use it for them square bar code thingys, doesnt seem to be useful for anything else. Not very good at finding like images.
Earth: Not sure if Maps need this to give sat data? but I never open this, Maps is much better.
Google Translate: Would be really good if I actually needed to know another language, but as is I just annoy people by using it to talk for me using text to speech.
Games:
Robo Defence: was kinda OK tower defence game, gets boring fast though even though you can upgrade your turrets I'm just not interested.
Fishin 2 Go: Pretty nice fishing game.
Alchemy: Combine elements to create new ones, very simple but good time waster.
Glyder 2: Uses orientation sensors to cortol a chick with wings around a map. Fun to explore and pickup things. Nice game.
Video Strip Poker: get a video of a couple nice girls removing a consecutive pieces of clothing for every $100 you take from her. Yeh its OK for what it is.
AnDrawing: good drawing program. Best I could find, ;latest update has shapes (square, circle ect.) though still doesnt have straight lines.
Surveillance:
Noise Alert: once the noise level reaches a set threshold it rings a preset phone number so you can tap into whatever the noise is.
OmniEye: Allows you to remotely view your PC webcam through your phone.
SECuRET Spycam: A motion detecting video/stil camera. When it detects motion it either takes video or a pre set amount of images and either emails them or saves them to SD.
Sca Lite: hides the viewfinder of your camera and prevents shutter noise, so you can discretely take photos.
Scanner radio: Recieves many worldwide emergency (police/fire/ambulance) radio signals, tap into most signals even here in Australia.
Seismo: A seismograph, not real useful but as it does nothing when it detects vibration. Only traces a line of it.
