Check this page with lots of free scores to download (scroll down to "voice and guitar") : http://earlyguitar.ning.com/page/scores-1
You can also search for the enormous french repertory from the early baroque (1590-1620) known as "Airs de cour". The songs are written for voice and lute but many of them can transfer to the baroque guitar. Composers like Pierre Guédron, Etienne Mouliné or Michel Lambert wrote many works in this style, which can be considered as the french counterpart of the famous "lute songs" by the likes of Dowland.
Hope this helps,