Not only a alternative, but one on steroids! Here are a few of the improvements.

The best of Tumblr and Reddit combined From Tumblr: Easy image browsing/discovery, reposts, likes, comments (and more) From Reddit: Everybody can contribute and post images.

Image blogging Effeciently blog images.

Forums Let the community actively contribute content.

Subscriptions Hide certain content for non paying users.

Customizable From hundreds of style related options to fully customizable html templates.

Fast and free Sites are fast and responsive and it doesn't cost your a dime.

And a lot more Forms, polls, galleries, folders, bookmarks, boxes, comments, widgets, users, themes, style sets, videos, awards, point levels, branding, invoice, offers, subscription types, etc.