I realize this group is low traffic, but it has a place in my heart.
There are now two free Android phone apps, one for flower
identification, http://goo.gl/lkOZf, and one for tree identification,
http://goo.gl/t5WyY (also one for birds, http://bit.ly/floweridapp).
They're tiny apps, based on my (fairly popular) ID programs on the web.