Lights Out

iPhone app that lets you put nearby Macs to sleep (discovery can be handled via Bonjour). Unlike iShutdown or Control!, it shouldn't require installing a special daemon on the Mac that's to be controlled. iSleep claims to do this via Remote Login (i.e. ssh), but the reviews seem mixed. If remote Apple events are still possible, then it should be feasible via that. If not (or as an alternative), whatever mechanism Apple Remote Desktop uses could be used here too.

apt-file and finding Ubuntu packages

apt-file can find which packages include a specific file. Ubuntu Packages Search also provides a web UI.

Freeze inactive background Chrome tabs

In the vein of the Firefox extension Dormancy, build a Chrome extension that frees up resources used by background tabs that haven't been accessed in a while. Using the chrome.tabs.onUpdated event, an LRU list could be maintained. Inactive tabs would have a screenshot taken via chrome.tabs.captureVisibleTab, and the tab would then be navigated to a chrome-extension:// URL that shows that screenshot (thus making all inactive tabs live in the extension's process, instead of separate renderer ones). When the tab is re-selected, history.back() could be used to back to the live page (by using history traversal, form/scroll position restore is invoked, retaining as much of the state as possible).

Optionally, there could be a browser action that displays the total/live/frozen tab count, in the same way that Tab Count does.

Derby

MVC framework making it easy to write realtime, collaborative applications that run in both Node.js and browsers.