The penpals section of the Japan Guide site had around 16,000 people listed the last time I looked, about 40 percent of whom are Japanese. Tokyo Friends is a fairly new website set up as a free searchable directory of people looking for penpals, friends or more. Mostly Japanese or foreigners who have an interest in Japan. Transpacific Dating Club is a new site for match-making between western guys and Japanese and Russian women. It's an online version of the Transpacific Marriage Agency.
Dandies is a correspondence and match-making agency for Japanese women and western men.
The Elite Introduction International website is a bit, if you'll pardon the expression, stiff. Let us know.