I am going to shoot a biography that will consist of a person sitting and talking. The video will cut to still images at various points. I was going to use a wired lav. Just curious though if handheld mics are ever used for this type of project.
Handhelds are pretty common among journalists, less so in documentaries. The biggest issue is usually that handheld mics tend to appear in-frame, although a handheld shotgun mic can usually be kept out of frame.
Handhelds are usually best-suited to "on the street" style interviews, where wired lav setup would be time-consuming and intrusive, and an overhead boom is out of the question. Dynamic handhelds also tend to be build like tanks, and omnidirectional handhelds are very forgiving in terms of placement and opperation.
If you would like to give handheld mic'ing a shot, here are a few mics you may want to consider:
Electrovoice 635A(B) - rugged and compact, very popular among radio journalists
Electrovoice RE-50 - an industry standard for video reporting
Sennheiser MKH416 - tranditionally a boom mic, but also works well as a handheld