There has been some discussions on the recent release of Rubber B straps for Rolex. I ordered one and just posted a review and installation guide at http://www.minus4plus6.com/rubberb.htm.
Below is an excerpt. I would post the entire review here, but there are many images and is somewhat detailed.
In June 2011, I came across Rubber B watch straps on buddy Jake's Rolex Watch Magazine. These straps are specifically designed as a Rolex strap replacement that utilizes the existing Rolex clasp. Like many of the other replacement straps, the cheezy buckle did not match both the watch and Rolex's quality level.
Seeing that these straps address the shortcomings of other Rolex replacement straps, I ordered one from Rubber B in preparation for a rafting trip that I am taking to the Grand Canyon. In my last rafting trip to the Grand Canyon,the band on the Rolex GMT that I was wearing did show some slight pitting from the gritty Colorado River water. For this trip, I wanted a band that was strong enough for the 7 day trip. In looking a the website at www.rubberb.com, I went ahead and ordered a strap. I spoke with Benjamin, who explained (in English or French, your preference) that these straps are made in Switzerland and are specifically designed for Rolex. Although the strap might be considered pricey for a "rubber" strap, Benjamin explained that the design work, testing, and quality are unmatched by any other manufacturer.
More of the review at http://www.minus4plus6.com/rubberb.htm