The places to start when researching any Scottish branches on your family tree:
General Register Office for Scotland http://www.open.gov.uk/gros/
Scottish GENUKI Pages http://www-theory.dcs.st-andrews.ac.uk/~mnd/genuki/scot.html
100 Most Common Surnames http://www.open.gov.uk/gros/surnames.htm
Tracing your Scottish Ancestry http://www.geo.ed.ac.uk/home/Scotland/genealogy.html
The Scottish Genealogy Society http://www.taynet.co.uk/users/scotgensoc/
Genealogy - Ancestor Hunting http://www-saw.arts.ed.ac.uk/misc/genealogy/ancestor.html
For general interest or to trace your roots "way back":
United Kingdom -- Primary Documents http://library.byu.edu/~rdh/eurodocs/uk.html - an interesting listing of historical documents online pertaining to the U.K.