The google-provided appstats is fine for profiling individual requests, but sometimes you need a much more comprehensive view.
With a Chrome extension to monitor the app engine dashboard numbers, and a small app engine app to collect data, I've managed to collect some interesting intra-day profile data, as well as provide a means for fairly accurate estimates of discrete operations.
Group view (for multiple app IDs). The artifact on the left is due to two days' worth of missing data. The lower graph has an obvious daily cron job, while the upper has much more distributed activity:
At some point I'll spin these out onto github if there's enough interest. The Chrome extension is based on the OSE (Offline Statistics Estimator) which scrapes usage data and applies customizable usage rates from the GAE dashboard pages.