Mediterranean and Alpine flora: http://www.mittelmeerflora.de/
Flora of the Mediterranean and Alpine regions (Portugal, Spain, Andorra, southern France, Corsica, Monaco, Switzerland, Austria, Italy, Malta, Slovenia, Kroatia, Bosnia and Herzegovina, Serbia and Montenegro, Albania, Macedonia and Greece).
Numerous photos of each plant species: 358 species of plants with 1617 photos (April 2015).
The key ("Bestimmung") is copiously illustrated and easy to use.
Although the text is in German, modern web browsers do a good enough job of translating to make the site usable, though the keys can be a challenge if you don't speak German.
The site is still under development (April 2015).