Nice idea for a thread, even though I'm running a fully unlocked phone now. Anyway, here's a few that I would recommend:
Battery Status - I've seen screenshots of some battery apps for WP8, and it looks like they're basically clones of this app. Let you pin a tile to show the battery percentage (with an option to update every 10 minutes, something not allowed in "official" store apps). Also has a cool logging feature that lets you view a chart of your battery drainage over time.
[APP] Battery Status (v4.6.1.1) - Telerik controls, icon sets, globalization and more - xda-developers
Supreme Shortcuts - similar to those apps that let you pin wifi and airplane mode settings to start, except that there are a LOT more options for shortcuts that you can pin.
[APP] Supreme Shortcuts - 2012-01-05 - Version 2.2.3 - French Language Fix + more - xda-developers