CycleGeek is a suite of graphing and analysis tools for cycling data (both heart rate and power are supported).
It's free, and you can upload and view your own files.
I wrote it because all the power analysis tools are expensive, and run on Windows. CycleGeek, on the other hand, is a set of scripts running on Linux, which can be accessed with any web browser. The graphing engine is gnuplot, and the scripts are PHP.
As this was and is a weekend hack, I have great plans for future features, with little time to implement them. Currently only Polar HRM files are supported. If you mail me a sample data file from another power meter I might get bored and add support for it.
This is an ongoing project, so it's bound to stop working from time to time, and/or unexpectedly get new features. I'm currently working on views by lap, calculation of maximum power efforts for a given time slice, and zooms-- plus, a few other goodies.
Upload your data file below. If you don't have one, click here to use one of mine. If you use the sample file, it will be clear why I program computers, and not cycle for a living.
If you have any suggestions or desired features, let me know. I may implement them.
A nightly tarball of the source is here.