[Brian]

Jwindsor - from the firewall settings you mention in your last post, it sounds like you're running Mac OS X 10.5 - if that's the case, you'll definitely want to switch to the "Set access for specific applications" setting. That lets you allow OmniFocus to talk through the firewall, but blocks other applications from doing so.

Think of it like giving a trusted friend a key to your house vs. leaving the door unlocked entirely. With the current setting, the door's unlocked. :-)

No experience with SplashShopper, but to allow OmniFocus to talk through the firewall, just press the small plus button towards the bottom of the preference pane. At that point, navigate to your copy of OmniFocus in the sheet that appears and we should be able to talk through the firewall.

If that doesn't appear to work, maybe there's something specific going on - perhaps print out this forum thread and wander to your friendly local Genius bar?