Okay, so Redditastic isn't technically an app, but it is a pretty sweet widget that lets you throw your favorite subreddits on one of your homescreens. Unfortunately it's only currently available for devices running Honeycomb or ICS, and it probably won't see any previous builds of Android simply because scrollable widgets aren't supported by them unless you use a custom launcher. That being said, if you do own a supported device, this Reddit widget is definitely one to check out.
What's cool about Redditastic is that it lets you create individual widgets for each of your favorite subreddits. You can also choose to have the feed populate with hot, new, top, and controversial threads.