We use TabTag for contact/calendar/folder sharing between computers on a
network, which works quite well and is very robust. www.tabtag.com
Otherwise you could try the Vaita "lite" version, which is free, and see if
it looks like it it will meet your needs.
Too bad Outlook never could successfully implement functionality such as
this. The "Netfolders" fiasco of earlier versions still looms large in my
memory.