Don't know if its okay to post this, because i'd be advocating "illegal" downloads and what not, but the Pirate Bay app and tTorrent are two underrated apps for me. I use Pirate Bay to find new episodes of TV shows, or new movies in great quality, or even albums or apps. Once I use Pirate Bay to find them, tTorrent extracts them to a folder on my phone and BOOM. Downloaded 3 episodes of Supernatural, Taken 2, and Flight all onto my phone in 30 minutes over wifi. Great quality for a lot of the shows too. Now when i'm bored somewhere, I'll always have movies/shows (or at least a means to download movies/shows) while I play the waiting game for maybe a flight or mechanic or something. No need for me to download on my computer, then drag it to my phone or fiddle with any of that. Just queue movies up to download, lay it down, and im good to go. When im done watching what im watching, I delete it and download something else. Never ending supply of movies on the go for me.
EDIT: Thought about a couple other great apps.
1.) Wallbase HD for wallpapers. EVERYTHING is super high quality and they have a TON of wallpapers in just about every category.
2.) Any.DO: Clean, beautiful task manager app. Honestly, when people talk about ugly apps on Android, this app makes me think people just aren't looking hard enough. Nice looking and functional, with widgets and support for lock screen widgets and syncing with google task.