It's a great and important idea to have some scale system to monitor asthma everyday to take control instead of letting it slide down without realizing early enough.
The Peak Flow Meter is a simple tool to monitor and measure; RRDTOOL can be used to record data for long-term report and analysis. -- Do I need RRDtool??
One thing worth mentioning is that a week-long trip to Aruba fixed my asthma and respiratory infection (for now) instead of prednisone or antibiotics -- the MAGIC comes from the sea (salt), the warm air (27-31C) and the sunshine!
More to come when I have some time to create the "app" for myself.