http://www.cmsmatrix.org/This provides a summary and comparison of many online content managements systems including the ability to rate systems you have used.
You can search for systems with specific features, licenses or technologies. In my opinion this could use a little work. Tried to search for all sites built using ASP.NET and several were left out because it is not a drop down select but a field that they enter. One was left out because of a typo where it said "ms aspnet".
You can compare up to ten systems in a side-by-side table. This can be handy!
Here is the current list of systems at the time of this posting:
Absolut Engine
ADXSTUDIO
Affino
AGPCMS
Apache Lenya
AquiferCMS
Ariadne
Arp.Site Free
Artiloo
AssetNow
AutoWebBuilder
autowebcms
AWF
Axinom Enterprise CMS
Axyl
Back-End CMS
BeYourOwn.net
Big Medium
Bitrix Site Manager
BLOG:CMS
BolinOS
Bricolage
Caravel
CathDesign CMS
chaseMe CMS
Ciamos
CMS Encore Pro
CMS Master
Cofax
CommonSpot Content Server
Composite CMS
conrad://
Cont'N'Shop
Contenido
ContentM
ContentServ
ContentX
ContentXML
contentXXL - ASP.NET CMS
Contribute
Conviveon SiteConnect
CPG-Nuke
Daisy
dbCanvas
DEV WMS
Direct News
DotNetNuke
Dozing Dogs ASP.NET CMS
Drupal
Dynamicweb
Dynasite - Universal CMS
E-Commerce SIBOX CMS
e-publish
e107
Easy Publisher
EasyConsole CMS
ECMSuite
eContent
edeptive™
EGOCMS
Ektron CMS300
Ektron CMS400.net
eNetwizard Matrix Server
ENID
Enonic Vertical Site
EPiServer
EPIX
Eplica
Esselbach Storyteller CMS
Estrada Web Technology
Etomite
eTouch CMS
Explid
Exponent
ExpressionEngine
eZ publish
finalsite
fipsCMS XL
FLUiD CMS
fly CMS
Freestyler
gee! Web Tools
Geeklog
GeoDocs
GiiCorp CMS
GYO
HardCore WCM
Harmonise
Honeycomb Archive
i-Web Suite
IceWEB CMS
ICMv2
icogs
imCMS
Immediacy CMS
Interwoven TeamSite
Isens Evolution
ISIPortal
Jahia
Jalios JCMS
Jetbox CMS
Kentico CMS for ASP.NET
Komodo CMS
Komplete CMS
Krang
Land Down Under
lemoon®
Libertas Enterprise CMS
Livelink WCM Server
liveSTORYBOARD CMS
lucidCMS
Magnolia
Mambo
MammonBase
Manifest
Manila
MARQUI
MD-Pro
Merge Portal
MeshCMS
MetaDot
Midgard CMS
Miraserver
MKDoc
MMBase
mmprove for publications
mmprove for websites
Moodle
Movable Type
multineo neOS
My Web Pro
Near-Time Flow
Nectil Publishing Suite
Netdoc
NetManager
NetPotential CMS
NPDS
NPS
Nucleus CMS
Nuxeo CPS
OmniUpdate
Open CMS
OpenACS
openEngine
OPENi-CMS
OpenPHPNuke
OpenPortal CMF
openshare
Opus
Oracle Portals
Pathos
PHP Nuke
phpSlash
phpwcms
phpWebSite
PHPX
Plone
PLS Manage-It!/YourWeb
pMachine Pro
Polopoly
Poseidon
PostNuke
Powerslave ECMS
Quantum Art Q-Publishing
Rainbow
REDAXO
RedDot CMS
Revize
Roxen CMS
SabreTooth
Saurus CMS
Scoop
SelbstdenkerFrameworks
Sharepoint Portal Server
Silva
Simplicis
Site & Content Manager
Site Unit CMS
Site Wizard
SiteBuilder
Sitecore
SiteKreator
Sitellite CMS
SiteRefresh
SiteSage CMS
SiteSapiens
SiteWorks Professional
Slashcode
Smartsite CMS
SpinPike Commerce
SPIP
SuiteWise
SuperCharged CMS
Synkron.web
Sytadel
Taggon
Tangora CMS
TCMS
Text-e
Tiki CMS/Groupware
Tikipro
Tonic
Tools for Organizations
TWiki
TYPO3
WAXTRAPP
Web Content Manager
Web Manager
Webbler
WebDB
webEdition
WebEngine v6
WebGUI
WebHare A.P.
WebPal
Websphere EIP
WordPress
WORKSsitebuilder
WYMSY
Xaraya
xBx Site Manager
XCMS
XHP - eXpandable Home Pag
Xitex WebContent M1 PE
Xitex WebContent M1 SE
Xoops
XPort
zeta producer
Zonus Engine