I realize this is a new app and all but are they making any good add-ons for it. I am trying to find a good ad-block add-on or perhaps a good download manager. I don't care about social site add-ons...Also a good gmail where if I click on a mail-to link it will open it in gmail for me.
IE9 includes a Download Manager! See...
What's new in IE9?
IE9 Top Features
As for "ad blocking," check out http://www.mvps.org/winhelp2002/hosts.htm