Below are a list of sites that I have frequented in my own journey as a soundtrack fan, and specifically for finding resources for poster artwork used in the making of these covers, as well as other terrific cover sites which have served as inspiration.

Soundtrack Review Sites:

Movie Music UK
 - Comprehensive score review site established in 1997, with excellent reviews by Jonathan Broxton.
 - One of the oldest and largest review sites, Christian Clemmenson's site is an iconic staple since 1996, familiar to most soundtrack fans, offering extremely detailed reviews and an infamously caustic wit.
 - Another staple for over two decades, James Southall's site is a terrific resource for short and hilarious reviews.

Art Sources:

 - for a low membership fee, maybe the largest resource for downloadable poster artwork.
 - great free resource, with large database of high-quality poster artwork and transparent film title PNG's and textless options.
 - another excellent free database of official film poster campaigns.
- free poster database, with official and fan-made collections.

Alternative Soundtrack Covers Sites:

 - Stunning boutique collection of custom soundtrack covers, and a great inspiration for this site. 
Alternate CD Art
 - great covers collection by Javier Burgos.
Album Art Exchange
 - free database of hi-rez community scanned official covers.
 - another great site for front covers and sets, huge library to explore.