Lightning Calendar - Organize your life — it’s about time!
Xfce - Xfce is a lightweight desktop environment for UNIX-like operating systems. It aims to be fast and low on system resources, while still being visually appealing and user friendly.
Calendar Lock PEA - Calendar Lock PEA is an encrypted desktop calendar with a day, week and month view. The shown calendars are never stored unencrypted on your disk, but exist only in the RAM. Platform-independent, Open Source, no installation or registration required.
LXDE - Why will you like it? Less resource needs. You can use it on your less-pricey embedded board or salvaged computer. Component-based design. Don't want something in LXDE, or you don't want to use LXDE but only part of it?
Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...
KDE Plasma Desktop - Plasma Workspaces is the umbrella term for all graphical environments provided by KDE.