We use Sakai - and if you know what you're doing (and sometimes even if you don't) you can add new SOAP calls, enabling you to write scripts to manipulate the system, and run maintenience.
There are a couple APIs that are exposed in Luminis via SOAP, the Targeted Announcement API comes to mind, simply because I've used it.
Has anyone use any of the other APIs, and/or created new SOAP calls ?
I would LOVE some user APIs - sililar to -
cptool list user xxxxx -a
cptool set user xxxxx yyyyy='zzzzz'
cptool list sessions (-c)
extensible services like would make manageing the system much more enjoyable.