The notes browser plugin works in firefox and internet explorer.
I think this started in Notes 9.
Not really found a use for it as email for example does not work in it. I think there is a server option to launch inotes if you click on the mail icon now.
http://www-10.lotus.com/ldd/dominowiki.nsf/xpDocViewer.xsp?lookupName=Notes+Browser+Plug-in#action=openDocument&res_title=Additional_informationcol_Troubleshooting_the_Notes_Browser_Plug-in&content=pdcontent
Seems you have to have notes installed to run it, so maybe to quickly use a low tech notes database wouldbe a good use.
notes:home
notes:workspace
notes:replicator
will launch it.
NB: Notes Client shoudl not be running when you launch it !
trouble shooting: http://www-10.lotus.com/ldd/dominowiki.nsf/xpDocViewer.xsp?lookupName=Notes+Browser+Plug-in#action=openDocument&res_title=Additional_informationcol_Troubleshooting_the_Notes_Browser_Plug-in&content=pdcontent