A good site to find middle names is the following:
http://freepages.genealogy.rootsweb.com/~hughwallis/Scroll down to the middle names section and then click on Scotland. You can then search for middle names alphabetically within each county.
This site can be very useful indeed - especially if you are tracing a rare name.
Here is one family I am researching:
Robert PHILP m Margaret LOCHTIE in Fife.
Their children:
Jane PHILP 1822
John PHILP 1824
Robert Lochtie PHILP 1825
Margaret PHILP 1827
Andrew PHILP 1829
Elisabeth PHILP 1831
Janet Lochtie PHILP 1833
William Lochtie PHILP 1835
Of course middle names were not always family names. As I recall, I've come across this particular middle name (Lochtie - very uncommon) where, in one case it was used to honour a particular friend, and in another honoured the minister who christened the child ...
JAP