As users create new variables and settings in SiteCatalyst, it would be awesome to ultimately use SiteCatalyst as the central location for keeping notes. Setting up a separate database or managing one copy of an Excel spreadsheet can get messy. But having SiteCatalyst hold this information for you would be great. That way as there is turnover in the users, all of that information is retained in SiteCatalyst and new users can quickly get up to speed on the implementation. This can also be used by consultants as they create solutions for clients.
The notes would not just be general notes, but specific to each variable (props, evars, events, etc).