Hi All;
I just had this question on how to create a new calendar with a custom column that I thought would make a good post. I’ll document the process in SharePoint 2010, and note any differences if you are trying to do this in SharePoint 2007.
1) Let us create the calendar.
SharePoint 2010:
Site Actions -> More Options… -> List -> Calendar
Note: in SharePoint 2010 you have an extra option to create a ‘Group Calendar’. This you to roll other SharePoint 2010 calendars into one master calendar. This option is not available in SharePoint 2007.
SharePoint 2007:
Site Actions -> Create -> Tracking -> Calendar
So why is it a list? good question… Essentially calendars are just a lists with many ways to display the same set of information. That display can be a traditional wall calendar like seen below…

or in a list as seen here…

it is still the same information just presented in diferent ways. that presentation is what SharePoint calls ‘Views’.
2. Now we can add the custom column for our information.
SharePoint 2010:
Select Calendar Tools -> Calendar -> Create Column

This will open a dialog box where you can create your own column, with the name you specify, and the options you want. I’ll create a new required column called ‘Market’ as a ‘choice’ type. Now as we see below whenever I create a new event it will look like this:

Next, if I modify it to my default ‘All Events’ view and add the ‘Market’ as the fifth column I can now see it like this….

From there I can sort and filter this view to my heart’s content.
SharePoint 2007:
Settings -> Create Column
This will open a dialog box where you can create your own column, with the name you specify, and the options you want. I’ll create a new required column called ‘Market’ as a ‘choice’ type. Next, if I modify it to my default ‘All Events’ view and add the ‘Market’ as the fifth column I can now see it like this….

From there I can sort and filter this view to my heart’s content.
–Javi