Danga list of clients

C++

apr_memcache

libmemcached

libmemcache

MemCacheClient (cross-platform, but primary focus on Windows)

Java

Java memcached client

.NET

.Net memcached client

.Net 2.0 memcached client

BeIT Memcached Client (optimized C# 2.0)

MySQL

MySQL Engine (experimental MySQL plugin to make MySQL store data in memcached)

Perl

Cache::Memcached

PHP

PECL/memcache (pear install pecl/memcache)

PostgreSQL

pgmemcache

Python

python-memcached and a pooling wrapper class for use in multi-threaded applications

Ruby

memcache-client (pure Ruby)

Ruby-MemCache (pure Ruby)

memcached (compiled, wraps libmemcached)

caffeine (compiled, wraps libmemcache, no license)