Android

Zillow
As the leader in mobile real estate, Zillow provides real estate data and info for all U.S. homes on the free Zillow Android App. See Zestimate; home values, Rent Zestimates, homes for sale, homes for rent, and more. Use Android's voice-search feature, plus built-in GPS technology, to search for homes as you talk, walk or drive through neighborhoods.
(need to see the homes? 503-302-2333)
Get the free Android app / IPhone App

Realtor.com
The only site that also has accurate information from the local MLS feeds, this site is a very popular and user friendly resource.
Get the free Android app / IPhone app

Trulia Real Estate Search
Also an excellent site for finding your next home. Search homes for sale and for rent, plus see homes that have recently sold. Perfect for buyers, renters and general lovers of all things real estate, Trulia's app is designed for house hunting on the go. Get the free Android app
IPhone app

Craigslist Browser
CraigsBrowser has an easy interface, fast navigation, and all the features for browsing Craigslist. Not as easily organized as the three sites above, but good to have.
Get the free Android app /

Real Estate 114
View apartment prices, price trends and floor plan using the location-based services.
Get the free Android app

IPhone

Redfin
The best MLS-powered real estate app. Get all the details and photos on every home for sale, then add your own pics and notes. GPS-enabled. Available in select areas. Get the IPhone app

Homes.com Real Estate Search
Use this speedy application to search for your next home using your iPhone or iPod Touch. A touch or two on your screen creates a custom search of nearby homes for sale or rent. See detailed lists or search by maps, and quickly refine your search by price, property type, features and more.
Get the IPhones app