There is a problem on the Euler project, www.projecteuler.net , which asks to find the sum of all values under a given number. Problems on the Euler project have a range of solutions, where at least one solution has a runtime of under 1 minute. A popular, time efficient algorithm that finds all primes...
Today I was reading an article in The Onion, Conquerors You May Have Missed , and noticed that the number for the ant looked like it might be a big old prime, or at least have a large prime divisor. (For reference, the ant is # 43,168,974,563,247.) There are a number of algorithms for finding this answer...
My article on programming REST services with F# and WCF went up at InformIT. Please go read it! http://www.informit.com/articles/article.aspx?p=1394625