PIM and Contact Management

Essential PIM

Powerful, full-featured email client and organizer for Windows with portability (run it from a USB stick).
https://www.essentialpim.com
https://www.essentialpim.com/download-free

Open Contacts

Open Contacts is an address book with CRM features.
http://www.fonlow.com/opencontacts/
http://www.fonlow.com/opencontacts/Download.htm

Mozilla Sunbird - Portable Edition

Sunbird Portable is a standalone calendaring and task management application.
https://portableapps.com/apps/office/sunbird_portable

Note: Development discontinued.