Android/iOS: Just as Webstagram made Instagram easy to browse on the Web, Negatives aims to provide the same function on your mobile phone. The kicker is that Negatives is more beautiful than the default Instagram app, although it doesn't offer the same functionality.
Negatives takes all the people you follow and showcases thumbnails of their photos as a film roll. You can swipe through this to view the images or tap on any for a larger view, complete with the caption and hashtags. You can also tap one of the hashtags to give you a film roll-view of all the images in that hashtag. You can like any image as well as check out the comments, but there's no way to write a comment yourself.
I've been using Negatives for a few days now and, as a passive Instagram user, it's the best mobile experience for the photo-sharing service. If you use filters and want to be a part of the social network, this isn't what you need; but if you just want to check out photos shared by people, Negatives is awesome.