We have always tipped mousekeeping $5/day. I just leave it on the nightstand with a post-it note that says "for mousekeeping". They are not allowed to take any money that's lying out unless it's specifically addressed to them.
We tip the ME driver $10 each way. There is a sign on the ME bus that says something like "gratuities appreciated", so we figured it was expected. We have also gotten drivers who did a good job of entertaining us on the ride. I figure if we hired a Mears shuttle on our own, we would be expected to tip, so why would it be ok to not tip just because the shuttle ride is free?
We also tip the people at the airport who help us get our bags from ME to the gate, $2/bag.
For dining, we double the tax, then round up. There was an episode of Friends where Monica was a waitress and she said you are supposed to double the tax, so that's what we started doing. Tax rates vary from place to place, but it generally comes out to about 18% and it's a quick and easy way to figure it.