Backshift is a deduplicating (variable-sized, content-based blocks), compressing (xz or bz2) backup program. Full saves and incrementals are pretty indistinct other than the amount of data transmitted, somewhat like with "rsync --link-dest" but without the huge number of hardlinks. It also de-duplicates large file content at a granularity of about 2 megabytes on average; there tends to be a unique copy of each file with size less than around 2 megabytes on average.
highest is a program that efficiently finds the n highest (or lowest) numbers in a list of numbers on stdin. The traditional way of computing this using GNU sort should have a running time of O(n log n), where n is the number of numbers to check. Highest should have a running time of O(n log m), where m is the number of numbers you want to keep. A graph comparing the performance of highest to that of GNU sort is provided.