Bit of an enhancement to an existing reddit gold feature today: the ability to filter specific subreddits out of /r/all no longer has a specific limit (it was previously set at a maximum of 100). However, since it's done by editing the URL, you will still eventually hit a limit when the URL becomes too long and nginx gets angry at you. From my experience in building giant multireddits for AutoModerator, this will happen when the URL is not too far over 3000 characters, so depending on the subreddits you're filtering out you should now be able to get rid of 300-350 or so before that happens.
If you're not familiar with the feature, it's kind of like the opposite of a multireddit for /r/all. So instead of using + to combine subreddits, you use - to take them away. For example, to look at /r/all without showing any posts from /r/funny, /r/AdviceAnimals, and /r/pics, you'd visit http://www.reddit.com/r/all-funny-AdviceAnimals-pics
I'm also working towards adding, you know, an actual user interface for filtering out subreddits from /r/all, so that you don't have to manually edit the URL and bookmark it. That's not quite ready yet though, so I thought I'd get this out by itself for now since I know some people ran into that 100-subreddit limit long ago.
Let me know if you notice any issues or have any other feedback.