Veusz is a scientific plotting package, designed to create publication-ready Postscript, PDF, or SVG output. It features an easy to use graphical interface as well as a command line interface and can be scripted or embedded in Python scripts. Graphs are constructed in a modular fashion from separate components. Datasets can be interactively modified or created from within the program.
Trojita is a Qt IMAP email client. It is a pure Qt4 application with no additional dependencies. It has a robust IMAP core implemented using Qt's Model-View framework. Standards compliance is a design goal. It has support for bandwidth-saving mode aimed at mobile users with expensive connections. In addition to the usual SSL/TLS connections, the server can be accessed via SSH. It has on-demand body part loading, offline IMAP support, and safe dealing with HTML mail (actually more robust than Thunderbird's).