Change your username - see Name Change FAQ

See your friends' average rating on artist pages - Enabled automatically; it is the "green bar" on artist pages. On album pages, it appears under the main rating.

See average track ratings for releases - Enabled automatically; you must be using the new album page to see track averages

See enhanced stats on your user page: collection by artist, genre, and ownership - click on "user stats" in the music section of your profile. You will see a completely new stats page with more details.

Allow users to comment on your lists - when creating a new list, select the appropriate checkbox.

See personalized recommendations when browsing genre pages - when looking at a genre page (Contemporary Folk, for example), there is a "recommended for you" section.

Customize RYM's fonts and colors using themes. - Go to your profile page and click "account" then "options" and choose a theme.

See genre and label information on your collection page, and browse your collection by label/genre. - same as above; account->options

Upload more images to your profile (up to 500), including animated GIFs - enabled automatically.

Extend number of shoutbox comments from 50 to unlimited - enabled automatically - when scrolling your shoutbox, scroll to the end and click the "load more comments" button.