Sardinian is a Romance language spoken on the island of Sardinia, Italy.
What makes it interesting is that there are actually 4 different Sardinian languages spoken there on an island of 24,000 km2 (9,300 sq mi).
The reason must be that the areas have been isolated by the nature in such way that their common ancestor language could evolve to different languages.
More (check out the sample verbs and compare the differences):