In Kiplinger's Personal Finance magazine, Katy Marquardt has penned an interesting column on niche businesses with unrecognized profit potential. One of the companies profiled is Pall Corporation of East Hills, NY, which is apparently making a bundle in filters and filtration:

"From purifying water to preparing donated blood for transfusions, Pall's filtration devices apply similar technology across a variety of seemingly unrelated industries."

It's a non-glamorous company in a non-glamorous industry - kinda like a razor blade company that keeps selling high-tech blades and razors to customers, says Kiplinger. In this case, it's filters and filtering devices.