I think you will find the month by month outline on American Pregnancy Helpful because it goes over the major developments you can expect in a very clear and precise way for the first year. The list includes motor skills as well as others (such as social) but since the most noticeable and "measured" developments that occur during the first year are generally motor developments, of course these are included clearly.
Specifically in regard to rolling over, it lists back to side as beginning to happen around month four, then stomach to back in month five and back to stomach at month six.
Of course you'll be aware that these are averages and all babies do exhibit differences from one to the next. As an example, I currently take care of an infant (eleven months) and his older brother (of three years). The infant can crawl but mostly chooses to "worm" his way around preferring an army crawl to one on his hands and knees. His brother was already walking at the same age.
For an even fuller description of motor development babies, the history of the study of motor development in babies, and some thought about the mental development accompanying the motor developments (and/or) why things happen in the order in which they do, you could also read this article (I have yet to read the whole thing myself though) which is extremely detailed.