Yes, old Howard P. has inspired a shedload of movies, some good, some bad, some a bit meh. Here are a few that range from respectful adaptation to thematic homage to... well, silly but fun.
THE CALL OF CTHULHU - A silent film by the HPL Historical Society, this is a spiffing effort. It succeeds in recreating the essence of early Hollywood, complete with stop-motion effects and old-school studio-based action sequences. A faithful adaptation, and a fun one, this is a labour of love that works damn near perfectly.
SPRING - About as different from the above as you can imagine, yet still replete with Lovecraftian themes. Like tentacles, ancient secrets, and weird miscegenation. Overall it's not so much a horror film as an offbeat love story with a whacking great obstacle for our hero. It's also rather beautiful - it's Italian setting is about as far from HPL's Vermont as you could get, but it works, not least when the star-crossed lovers visit Pompeii.
DIE FARBE (THE COLOUR OUT OF SPACE) - This German film tackles the obvious problem with the original story - how to show a new colour on screen? The solution is simple - make it a black and white movie, have 'normal' colour represent the cosmic tint. The German setting works well and the acting is never less than passable. No tentacles, though.
DAGON - Here's a contentious one. For some this Spanish-set version of 'The Shadow Over Innsmouth' is just plain wrong. For me it's a fun version of a tale that is obviously pulpy in more than one sense. Stuart Gordon is good value and the overall 'feel' is right - the Spanish fishing port has a dank grimness that is pure Innsmouth. Plus, we get a veritable ton o' tentacles!