Besides the already existing text box for a description of the event, it would sometimes be nice to be able to add documents or links of any kind to an event.
Some ideas:
A drag'n'drop zone labelled "Drop files here" below the description box where you. It should accept any sort of file and use BRoster's Launch() to open the associated preferred application. Apps, too, can be dropped there.
Normal drag'n'drop should create a link to the dropped file, a right-click-drop could open a context menu to offer "Copy file" besides the standard behaviour of "Link to file". Linked files get a little overlay icon in a corner. Copied files are put in an event-specific subfolder in the Calendar settings folder. The folder gets deleted with the event.
The dropped icon gets a tool tip defaulting to the dropped file's name.
A context menu on a dropped file offers to "Edit info" (to edit the tool tip), "Remove", "Remove all" and "Open location" (opens the parent Tracker folder).
Clicking into an empty part of the drop zone opens a file dialog "Add attachment...".
Standard icon size is 32px, adding more attachments than fit in one row could shrink icons until they fit again. Minimal size is 16px, that should make more than enough space. Frankly that amount of attachments sounds unhealthy, people should better link a folder holding that many documents... :)
Besides the already existing text box for a description of the event, it would sometimes be nice to be able to add documents or links of any kind to an event.
Some ideas:
A little mockup: