I highly recommend TPI Astro's range of tripod spreaders:
http://www.tpiastro.com/
Very professionally-constructed in brushed aluminium.
Obviously costs rather more than, say, Barry's DIY solution, but what's cheap in this hobby?!
I bought one for an NEQ6 Pro & it works a treat - adds great stability.
And it folds up with the tripod legs, so once it's fitted, you don't have to keep re-fitting.
And the bloke (Dave) who runs TPI is a gem: he really goes out of his way to make sure you are happy with the product.
Dean