What sort of rules would you use for the Crimea? Last time I was going to wargame it we were going to use the ACW Fire and Fury rules with the mid 19th century Europe modifications published here. However they are a little complicated for my brain so I would be interested in seeing if there's anything else out there. I like free so 'Days of Empire' might be worth investigating. If 15mm is your bag maybe try Stormed at with Shot and Shell
This Yahoo Group looks worth investigating with downloadable rules.