I made this a few years ago to test hosting ASP.NET MVC in Azure...
Currently hosted here: http://jcapriotti.cloudapp.net/#/Home/Solve
I used this to help solve Killer Sudoku puzzles. Given a desired sum and how many terms make up the sum, it calculates all the possible terms that yield the sum. You can optionally provide terms that either must or must not be included in the results.