If you're trying to watch some TV via Slingbox right now and can't, don't worry, you're not alone. A support thread on Slingbox.com lays out the problems: Trying to access watch.slingbox.com directly, logging in to the Sling site, or trying SlingPlayer
via computer or a mobile device results in a page that doesn't load. Luckily, there are a few workarounds available like switching networks (some have said going from WiFi to 3G on their mobiles works) or using an older version of SlingPlayer that connects directly to your box and bypasses Sling servers. Obviously Sling technicians are working on the issue, but without any ETA on a fix, it's probably a good idea to check the thread and make sure your setup is foolproof before taking off for the weekend.
[Thanks, James & Dave Zatz