undrline via OfficeKB.com u28594@uwe wrote:

Microsoft Works has a standalone application that allows you to see
reminders even when the full client is not running or active
(wkcalrem.exe).

Searching, I can't seem to find a free app or plugin that:
1) is free
2) can do this for Outlook for a Microsoft Exchange Server account
(not POP3, IMAP, or HTTP)
3) that I can install without administrative rights (basically
anything that lets me choose where I can install it, and doesn't
write to the registry)

I don't know of anything fitting your criteria.
--
Brian Tillman [MVP-Outlook]