Node Notes
The idea is basically, anywhere in Blender there's a node, include a 'notes' icon that opens a notes panel to enter/edit/view any notes associated with that node (for documentation purposes). This allows for a nice place to put an explanation so that another dev can understand the meaning (or you yourself remember the meaning 2 weeks later ...)
3 Comments
Every "thing" in Blender should have a field for notes. Other well respected programs have this.
Probably wouldn't hurt to have this near the annotations tool, since they're fairly similar to each other.
Even have notes anywhere in the node tree itself. So a Note node :)