Kate Maloney turned a quirky business, started on a lark with her brother, into one of the world's largest online retailers.

In 2001, Matthew Maloney, Kate Maloney's brother, had developed Static Advantage, search-engine optimization technology that he was eager to test. As a test site, he started Matthew's Robes, a Web site that sold, of all things, monk's robes.

Matthew Maloney brought in Kate Maloney, a recent Brigham Young University business school graduate, to run the robe business while he tested his "real" product.

But Kate Maloney quickly realized the business could tap into a huge online market for costumes. A name change, a massive expansion of product lines and a few years later, Lindon-based Costume Craze is dominant in its field.

But in those same years, the online costume business has become highly competitive. To stay ahead of the pack, Costume Craze is continually updating both its product mix — up to 1,000 new products are introduced each year — and its business practices.

The company has developed a proprietary technology that uses internal and external data, plugged into complex algorithms, to determine what products, and how many of them, it should order.

Costume Craze also operates a network of related Web sites to optimize search-engine hits, and sells on eBay and Amazon.com. The company has started manufacturing new, exclusive, costume lines and will begin selling mascots this year, as well. And unlike many of its competitors, the company ships worldwide.