Domain names are inherently valuable for their brandability, and for what they can do to increase the visibility of your online presence. A domain that succinctly describes a product, service, or company is inherently valuable, as are domains that can be used across multiple markets or industries.
If a generic name isn't what you're looking for, unusual names and word combination are also popular. These may not describe a product, but they are memorable and can be molded into lasting brands.
High quality domain names sell for thousands, tens of thousands, even millions of dollars. Quality domains are becoming a hard item to find, with their values increasing year over year.