Rtl_power is a unix-hacker's approach to the waterfall. Its unique features include:
- Unlimited frequency range. You can do the whole 1.7GHz of a dongle.
- Unlimited time. At least until you run out of disk for logging.
- Unlimited FFT bins. But in practice I don't think I've taken it above 100k bins.
- Quantitative rendering. Exact power levels are logged.
- Runs on anything. A slower computer will use less samples to keep up.

The blog has a lot of other interesting articles, e.g. http://kmkeen.com/tiny-code/, http://kmkeen.com/flash-recovery/ , http://kmkeen.com/fp/ just to name a few.