I've found a really good review website that's helped a lot with the registry shopping. It's a site that basically reviews all the other review sites and comes up with the lists of the best products:
http://www.consumersearch.com/
For the first several product types I checked what they said against other reviews both profession and user submitted and came to the same conclusion. I also tried the reverse, picking a product without looking at their site, in this case digital cameras, and then went to their site and found out my pick is the same as their pick. So now that I trust what they say it only takes me a few minute per product to pick what I need. The frustrating thing is when none of the registry stores carry and of the suggested picks.
