Steve Gibson is a well known security expert who is the brains in the excellent "Security Now" podcast.
He knocked up a web utility to help you detect whether your company might be intercepting your HTTPS traffic with a man-in-the-middle attack.
( installing the own root certificates, so they can create fake facebook/gmail etc certs )
GRC Fingerprints link
Basically he lists the HTTPS cert fingerprints of known websites, eg. Facebook.
www.facebook.com *.facebook.com F5:6B:F2:44:63:B0:BD:61:36:C5:E8:72:34:6B:32:04:28:FF:4D:7C
www.boards.ie *.boards.ie C7:13:71:7A:A1:0B:CE:37:B1:77:46:FE:27:F1:58:A0:76:28:8D:42