What are some php cache related modules for drupal 7?
For opcode caching APC, Zend Optimizer, and OpCache are totally transparent to the application.  If you have them installed and enabled, Drupal will use them whether you like it or not.  There are some configuration tricks you can do to use them better, but this is really system specific.  For example, to help save memory, some users will filter out .admin.inc files from APC so they never get cached.

I am using OpCache on my PHP 5.5 servers.

To confuse matters, APC and Zend provide user caches which can be used as alternate cache backends to replace and/or supplement the database cache mechanism.  I would not recommend APC for this.  Memcache and Redis are the go-to solutions for these.  MongoDB can also be used, too.

My PHP 5.5 servers also have APCu installed just in case there is anything that may be using it.  Last time I checked, the Performance module would use APC user cache for stats.