I found some options that may work for you while looking for waterproof camera cases earlier today. Assuming it fits, you can operate the capacitive touchscreen through the plastic membrane. [Actually, you can operate the screen quite well through a Zip-lock bag.
] Pressing the power button may be tricky, but I'm guessing you could use the call/hangup button on a wired headset or bluetooth of course.
Overboard Case w/Armband $64
You'll need to double-check the size. There were less expensive variants
without the waterproof headphones.
As for skipping the keyguard lock screen, I use a Tasker
profile to disable it while driving / at home / etc. If Tasker seems too complicated, Locale
is its more user-friendly but less powerful predecessor.
Hopefully this helps.
[The long-haired red-headed guy with glasses]
HTC Strtrk [WM6.1] — HTC Shadow [WM6.1] — Samsung Galaxy S (Vibrant) [2.2 Axura] — Samsung Galaxy Note [stock debloated UCMD3] — Samsung Galaxy Rugby Pro [stock UCBLL1]