This is the only link I've found, but it doesn't work.
Where can I find a precompiled dll for the php_memcache extension?
Here is the pecl page( you will have to compile it for your specific PHP version otherwise it may encounter problems): http://pecl.php.net/package/memcache.
If you're running PHP 5.3, here's mine : http://www.box.net/shared/tvb0i6gj6y (x86).
Currently the PECL side is being recreated in order to provide better builds. This is needed as the PHP on Windows build process has been improved massively, like using new compilers and supporting 64bit versions.
Temporarily Windows builds of PECL extensions are made in a "on need" base and are provided at http://downloads.php.net/pierre/ if your extension is missing/outdated ask on the pecl-dev or internals-win list (both @php.net) in a friendly way.
The new site should become available soon.