There are certainly a lot of monitor-y things out there and they just
didn't fit my need, so maybe this will fit someone's besides mine.

pbxmonitor
pbxmonitor.db

The first one is a php script and the second is a flat file of extensions 
to extension name mappings of internal users.  It contains example data 
that needs editing to fit your scenario.

so the pbxmonitor.db might have (separated by tabs):
SIP/2000	Receptionist
SIP/2001	Username 2
SIP/2002	Username 3

an internal call might say:
Username 2 talking to Receptionist

an outgoing call might say:
Username 3 talking to 18005551212

an incoming call (already answered) might say:
18005551212 talking to Receptionist

It's pretty self explanatory I guess.  Run it and hope it does stuff.

so, pbxmonitor, in our application, is called from watch, like so:

watch -t -n 1 pbxmonitor

but you could implement it into a refreshing webpage or otherwise parse 
it for your needs.

[sidenote]
We use putty to connect to the asterisk box, and there's an account 
called monitor with a key login instead of password login, and the 
monitor user's .bashrc runs this watch line at startup, followed by an 
exit.  I call tell putty to auto login a username, and via the command 
line, make it load this connection at startup without asking for any 
info, so it's pretty seamless for the end user.  But all that is neither 
here nor there related to my post.
[/sidenote]

I don't have parked calls in yet, but will soon.  I don't have meetme 
conferences in soon, don't know if I will.  It doesn't do non-bridged 
calls yet, this will be soon, as it is important to us.  This should 
give indications of people checking their voicemail, people in echo 
rooms and meetme conferences, and people in IVR things. Not sure what 
else I'll have in it eventually, we'll see.  It's only tested with SIP, 
IAX should work but dunno. I'll post back when I improve it.

Comments, suggestions welcome!

Moj