TED talk: Algorithms that shape our world

Kevin Slavin talks about how people will one day terraform the earth just to make algorithms get access to data faster. Talks about how algorithms
 i. on Amazon.com caused the price of the book "The Making of a Fly" to become 23 million USD
ii. caused 9% of wealth of US stock markets to disappear in the Flash Crash of 2:45

Summarize large amounts of frequency data in sublinear space

Count Min Sketch is a sublinear space datastructure which can be used for approximate answers to data streams for points, ranges and etc. It can be used for finding the most frequent items (approximately) and also extended to find anomalies or differences in streams for monitoring.
Original paper: http://www.eecs.harvard.edu/~michaelm/CS222/countmin.pdf
Related paper: Finding significant differences in Network Data Streams

Discussion on Spatial indexing algorithms

For people interested in Spatial Databases there is an interesting list of algos used for indexing (Quadtrees, Geohashes and Hilbert curves) at http://blog.notdot.net/2009/11/Damn-Cool-Algorithms-Spatial-indexing-with-Quadtrees-and-Hilbert-Curves

LZMA algo and XZ Utils

XZ Utils is a data compression software with pretty high compression ratio. It uses the LZMA algorithm and has much better compression ratios than bzip2