You can now temporarily turn off sites by going to Manage > Mute Sites. This is for those feeds you want to keep but ignore for a while.
I use this to mute craigslist feeds that I no longer want to see in my unread stories list, but I want to keep just in case I need to perform a specific craigslist search without having to go through the whole process of recreating the RSS feed.
It’s also useful for subscribing to high volume sites and only reading them when you want to know what’s happening but without having to remember to re-subscribe. Such a simple feature but with a ton of utility.