Nice little application, works wonder with social media sites that I always want quick access to. More complex sites that utilize certain plug-ins are a drag at times though, such that they may not work without tweaks here and there, or not even at all. Netflix Instant and HBO Go are some examples.
I came across a solution for getting Netflix Instant Streaming to run on fluid: Change the default User Agent in the plist file. Instant will run if you change the User Agent from default to Safari, but it reverts back with every start up. To change that:
Right click the fluid-created Netflix app, and go to Show Package Contents. Go to Contents folder, then Resources folder, then open UserAgentStrings.plist up in your choice of editor (in 10.6.8, I used TextEdit). In the "Default (Automatically Chosen)" string, the default is listed as "Mozilla/5.0 (Macintosh; Intel Mac OS X %d_%d_%d) AppleWebKit/%@ (KHTML, like Gecko) %@ Version/%@ Safari/%@". If you look below, there's a whole host of other strings, such as Safari, iOS Safari, IE, Firefox, etc. Figure out which one enables Instant for you, copy that string, and paste it in the place of the default. Save the plist, and reopen the Netflix app; Instant should now work. Not sure if updates will bork this trick, but quitting the application certainly doesn't.
As for HBO Go, I haven't figured that out yet. Whenever I try and login with my provider, it jumps me to Safari and the HBO app remains on a grey page with no activity. If anyone can give some advice, that would be lovely.