All digized music in the Royal Danish Library is, in principle, available from here:
You can subscribe to a newsletter ("nyhedsbreve") from the musicdepartment here
which includes an archive of newsletters.
Example: In the latest newsletter April 2006 , there is a link to the latest two months of additions, called
"digitale noder i februar-marts", for instance. (Currently linking to here:
http://www.kb.dk/kb/dept/nbo/ma/acclist ... -04-06.htm
These additions ("nyanskaffelser") are including all, thus you must select music specifically for guitar yourself from here.