One thing that I miss the most on my Android devices is an open source office suite that can open ISO approved .odf files. All office suite default to controversial .docx or .doc format. The good news is soon there will be open source office suites for Android which will have native support for open formats. LibreOffice will come out with its own suite for Android later this year. Now, Calligra developers are also working on porting Calligra to Android. KDE developer Mek is working on getting Calligra work on Android. The app is based on QWidget and is working fine on a N900. There are still some issues that the developer is working on. He has created an .apk file which you can download and try on your Android (3.x/4.x) devices.