Charles Harrison is working on a dissertation pertaining to Yew Trees in the UK and needs help collecting data. He is using an interesting iphone/android app called epicollect to allow anyone to submit Yew photos and relevant data(i.e. trunk width,location) via their phone. That data is then displayed online via the Yew Hunt project page.
If you live in the UK and are interested in helping Charles out, below are complete instructions on how to get started Yew Hunting.