This is actually pretty cool. Citrix recently launched the new "Citrix Ready Community Verified" portion of the Citrix Community site. Unlike a lot of vendor "ready" programs that are just a shakedown for payments from ISVs to be certified, this portion of the Citrix Ready site is powered by the community. The idea is that you add the applications that you've been able to get running on Citrix into the database. If someone else has already added your app, you can "verify" it by adding a vote. (Kind of like a digg.)
You can specify what OS, version, and type of Citrix product you're certifying the app for. And there are conversations / comment threads for each app in the database so you can discuss or post any installation tricks you've figured out. Right now there are 919 products in the database. You can also search by Citrix product version, enabling you to, for example, search for all products that people have certified for XenApp 5.
I should point out that this cool thing I'm talking about is the "Community Verified" section of Citrix Ready. There's a regular "Citrix Ready" program website that's one of the more traditional pay-to-play ISV program that's not too valuable. But the community thing... very nice!