Youc an generate a nice list of 'participants' using:
{contributors:mode=list|showCount=true|showLastTime=true|showAnonymous=true|order=update|include=authors,comments,labels}

I would like to generate a similar list of observers, using:
{contributors:mode=list|showCount=true|showLastTime=true|showAnonymous=true|order=update|include=watches}

which would allow me to make a user macro that renders:

Participants
- James Mortimer 19 (14 mins ago)
- Shannon Krebs 3 (2 hours ago)

Observers
- James Mortimer
- Somebody Else

*** add the 'watches' parameter to the 'include' option of {contributors} which collects names of people that are watching a page.