I really like Citrix Xenapp 5′s ability to publish app’s by streaming them to the server. For those not familiar with this you package the application (office, etc) using the citrix app packager. Place these packages on a file server somewhere and then when you publish the app just specify stream to server and refernce the network path of the package.
First this makes life easier in deploying new citrix servers. Second it means you can deploy software that normall wouldn’t work together (office 2003 and 2007 for example) from the same box. It really keeps your citrix servers neat and clean.