Android only: Using a task killer to constantly wipe apps and save battery is not a smart strategy. Watching out for the occasional CPU-killing app makes more sense, and that's just what Watchdog Task Manager does with smart alerts.
Watchdog runs in the background, watching for apps to start using more than a certain percentage of CPU power that you specify (with a default of 80 per cent). When it notices an app going out of bounds, it notifies you and offers options to kill the app, ignore it or add it to your "Whitelist" of pay-no-mind programs. By default, Watchdog doesn't use much power itself, only checking in every two minutes or so, but you can make it run more real-time if you'd like to really pin down a problem you know is happening.
If you're wondering about a long-term solution to apps that drive you nuts and seem to suck down your battery power, consider this summary of an informed Reddit post:
Use a task manager wisely because Android has no idea when you are no longer using an application, use AutoKiller to better configure Android's memory and process manager, and most importantly use a startup manager (Autostarts) to configure what applications start when your phone boots, and please tell everybody else about it. Use a better launcher if your phone comes with a crap one.
Watchdog Task Manager Lite is a free download for Android phones, with a paid version ($US3.49) removing all advertisements. You can grab the Lite version with your phone using the QR code at right or by searching the Market for "watchdog" or "zomut".