On most phone platforms, the user never sees the URL where the app's data and procese are hosted -- so the domain actually has limited potential in that regard.
It's like the social games -- most of the major game companies only bother with domains to protect their trademarks. Most of the actual traffic comes from within Facebook/MySpace/etc. and the players generally don't actually see the domain name, so the domain has only limited appeal from that standpoint.
As an online directory/comparison, a business site catering to taxi services who wish to be featured on one or more taxi apps, a lead generation service etc. it has potential, but not sure to what extent that would add value to the domain over any other brandable/similar name.
Low value, "domainer" kind of domain in my opinion, ie. low-mid $xx
Frank