Meet Zone DPMX: a wearable power meter for cyclists that attaches to their shoes and can be moved between bikes easily. The device measures your power and cadence as you ride and sends the data to your ANT+ bike computer. There are two version of the power meter available (single and dual).
Since you can use this power meter on all your bikes easily, you get more consistent readings. The projects is quite popular on Kickstarter right now.