Over the past few days there has been quite a lot of interest in my Kitten Blocker for Firefox. Thanks to Martin Belam, Tom Cox, Ms Slide (site possibly NSFW, depending on where you work, I suppose) and everyone who's shared, blogged or passed the link around on Twitter. It has now blocked well over a hundred inadvertent visits to the Mail online, and the original Tea and Kittens site just served up its 20,000th kitten.
The original extension, Kitten Block version 1.01, is available on the Mozilla site, and works for any version of Firefox up to 3.6.x. I've had no reported problems, and it has now been tested on dozens of Windows and Mac systems. For those testing out Firefox 4 Beta, though, it'll refuse to install. This is a limitation of the installer package, rather than the code.
I'll update the Kitten Block package to 1.0.2, with support, once Firefox 4 exits beta and I can test it on the final version. In the meantime, here's a working beta version – I've tested on the current 4.0b6 (and 3.6), and I've set the package to be valid up to 4.0b9.
UPDATE – Version 1.1, on the Mozilla Update site, now supports Firefox 4 beta.
UPDATE 2 – Firefox 4 has launched, and is supported in full by v1.2