What iPhone/Android apps are used for research and data collection?

You should take a look at a host of applications that are listed here: http://humanitarian-nomad.org/online-selection-tool/ Not all are necessarily the most reliable and tried and tested. But the ones I could vouch for are ODK and SurveyCTO. Really excellent applications for rigorous offline data collection in field and research settings, built by researchers for researchers (unlike most of the apps in the other answers, which are market research applications that people are pushing to be used in a field setting without an understanding of the needs and context of serious research vs market research). ODK is free and open-source, but a little rough around the edges and requires a bit of time to set up and install since it is just the open source platform and you have to figure out your own server set up to use it. SurveyCTO (http://www.surveycto.com) is a more professional, polished tool based on ODK and is an off-the-shelf, pre-hosted version, so the work has been done for you (but it isn't free). Full disclosure: I work for SurveyCTO.

I work for a company that makes an app called FormMobi, which combines data collection and CAD sketching.  Because it's fully customizable (you have the ability to design your own forms) it can be used by anyone from researchers to contractors to inspectors and more. There are Enterprise solutions that combine API so you can push data into back-end systems too.  Learn more at http://www.FormMobi.com.

Have you tried QuickTapSurvey? We are a mobile survey and data collection app for the iPad and Android. Users can create their own surveys and gather responses using tablets without an Internet connection. You can sign up for a free account here: http://quicktapsurvey.com/

I do a lot of social research 'in the field'. For not having the time consuming data-entry (paper to excel /SPSS) and not finding a suitable mobiel app, i created dbapocket. My researchers have one or more digital form(s) on their smartphone. Results can be downloaded online or pushed into a dashboard like BIME for viasualisation of the data (monitor, analysis). Basically ANY form can be made. I guess it can be used in non research environments (inspection, measurements etc). The app's (Androiud, Blackberry) are made for fast and easy use.

Take a look at MetricWire. We have a web interface where you can design your study personally without having to talk with a developer. Also supports geo-fencing and location tracking. The app can also run in the background without the need to be connected to an internet connection, and send push notifications/reminders when needed.  http://metricwire.com/