The last I heard, Apple had over 100,000 applications available for the iPhone. This list will just scratch the surface, but will highlight some useful home searching and buying apps. If you are not an iPhone user, other phone companies and devices will have either the same or similar applications for your phone. All apps described here are free with upgraded versions listed where available.
Realtor.com - A great application that puts the power of the #1 most visited real estate web site on your phone. It's a nice tool that takes a little getting used to. Users can search for homes, look for open houses, map listed homes, save a home search, and even e-mail a listing agent. I am still finding out all that it has to offer, but I think it's a great supplement to online searches or a good on-the-go tool if you don't have access to a computer.
School Finder - The app gives you a long list of types of schools to choose from using your current location - high schools, elementary schools, cooking schools, etc. Choose a category and a list of schools will appear. Select a particular institution and a map will appear with the address and phone number.
Near Supermarkets (Yeerp) - Like the location of a house or neighborhood, but wonder how far the nearest grocer store is? The app can use your current location or you can type in an address or ZIP code. A list of supermarkets, convenience stores, and similar businesses will appear. From there, options include calling, saving, e-mailing, mapping, etc. the store.
CalcsFree Mortgage Calculator - This app offers everything from simple calculations to detailed information regarding home payments. Calculations can include home insurance, property taxes, PMI, HOA fees, and more. Other functions include estimated tax savings, amortization charts, and total cost of a loan. An upgraded version, CalcsPro, is $0.99.
Offender Locator Lite - Concerned about potential offenders near a home? Use your current location or type in an address or ZIP and this application will give you a list of up to 10 registered offenders. This app is useful as an additional tool to the Department of Corrections web site. The Lite version limits the search results to 10, but the full version shows them all and is available for $1.99.