In real estate, "desktop valuation" is a term used to describe a limited (and sometimes fully automated) process of estimating the value of a property. Most notably, desktop valuations are a type of appraisal that does not involve a physical inspection.
These types of real estate appraisals are typically used for residential properties, located in relatively stable neighborhoods with a sufficient number of recent and comparable sales. It is assumed, among other things, that the home is in reasonably good condition.
In business, the term is sometimes used by investment bankers to describe a preliminary estimate of the value of a private company, based on limited information. That information typically includes recent financial performance, forward projections provided by the company and a general understanding of the subject company's business, competitors and industry, derived from the investment banker's prior knowledge.
These types of business valuations are typically used to provide companies with a high level and broad estimate of how it would be valued as a public company. The valuations are also typically provided "...subject to further due diliigence" which would include, among other things, discussions with management, a more detailed examination of the financials and adjustments to the valuation based on information specific to the company.