Today I gave Josh a knitted iphone cover to match his headphone cover.
I didn't take a picture of it, but it looks pretty much like this (except knitted instead of crocheted):
I basically just cast on enough stitches so the row would reach around the phone, and then I just knitted garter stitch until the piece was big enough to cover the phone, and then I stitched the bottom and open side closed.
There are plenty of patterns on how to make a phone cover online. The pattern for the covers in the image above is made by Roses'nLillies.
There's also this fun iphone sweater by ColoradoMoms:)
or this felt cover by Wild Olive:
They are all really easy and fast to make.
I also made another little pair of mittens today:)