I've tried a lot of free apps to suit cheap Android devices (Archos5, Archos 43, ZTE Skate). Here is what I've found. I also prefer reasonable app size and some kind of minimalism.
- APV PDF Viewer
- Simple but neat PDF viewer.
- Folder Player
- Simple audio player able to play folder contents.
- Jota Text Editor
- Forget of fancy task/notes managers. Get organized by simple text files instead.
- GPS Status
- Simple tool to see how bad your phone GPS is. ;) Also provides simple navigation to given coords (usable for geocaching or remembering where your car is).
- Usable but still simple image gallery (supporting intents!)
- Simple tool to make alarm/ring tone from mp3
- Business Calendar Free
- Nice Google Calendar replacement.
Games & amusement
- Roguelike gem.
- Pixel Dungeon
- Roguelike gem. Fancy looking, but hard a bit.
- Excellent space shooter in classical form.
- Perfect Piano
- Best keyboard app I've found. No (or minimal) sound lags even on slow devices.
- Choice of Broadsides
- "Choose your adventure" style game. If you'll like it, check other games from Hosted Games & Choice of Games LLC.