There's a potentially large canvas to cover. The InternationalCouncil of Shopping Centers says the 28 retail chains it tracksclosed 2,122 stores in the first three months of 2008. For WindowGain, those businessfailures are possible sources of revenue.

Even in a slow economy, some commercial real estate focusedfirms are staying busy. Industry experts say the key is developingunique or improved solutions for niche markets, with a focus onincreasing revenue. New York City-based On Deck Capital,for instance, developed financial products and technology that'senabling it to offer "performance-based loans to businesses thatmay not have access to traditional bank financing" in 45states.

Companies like RealPage Inc. of Carrollton, TX target multi-familyproperty owners with software designed to take the guesswork out ofresidential rental rates. RealPage boasts the program helpsproperty owners increase profit. It just sold its revenuemanagement software to Essex Property Trust Inc., a Palo Alto-based REITwith 133 communities, mainly on the West Coast.