In my brand new Summer ’08 pre-release dev environment I created a formula field on Opportunity that looks up to the related Campaign:

IF(NOT(ISNULL(CampaignId)),HYPERLINK("/" & CampaignId, Campaign.Name ),"")

Which is a hyperlink to the Campaign to which an Opp is related.

Why, you might ask. Because for some reason, Campaign isn’t available in the Related List for Opportunities on the Contact Page Layout. And sometimes it’s nice to see giving history along with the Campaigns those gifts came in from. I had a customer ask me for this today, as a matter of fact.

Would be even nicer if I didn’t have to fake it, but this will do.