best posture for modeling is actually both legs and arms only slightly away from the body (about 20degrees), doesn't make the actual modeling any easier, but it's what the reference animation pose should be to make sure that you can have the entire range without vertex stretching.
if you want to see some good reference images then check out bobotheseal.com, as he generally makes some good 3qtr turn arounds. Titan (paul lasalle) used to have some good ones too, but his site is down atm.
i have a habit of trawling some of the professional concept artist sites to see what new personal work they've done as a challenge to make. going to be doing one of the new ones from bobo's site soon for kicks ^_^