Peer Wandel Hansen has created a number of virtual keyboards:
Do you want to write the letters and scripts from around the world, then pick from the list below. The message you write can be included in Web-documents and Email without using Graphics or extras. Use the “keyboard” at the bottom of these pages and copy’n'paste the HTML codes to your Email or HTML program. Try my Multi Language Virtual Keyboard where I remap your US-keyboard to write some of these scripts. If you see a lot of ??? below, your browser is not supported.
The scripts are Arabic (العربية), Japanese (ひらがな, カタカナ), Greek (Αλφάβητο), Georgian (ქართული), Armenian (Հայերէն), Hebrew (ורמ – עברית), Korean (한국어를), Indian (Devnagari, देचनागऐ), Chinese (汉字练习纸), Russian (Кирилица), pan-Ēŭŗôpěąņ enhanced alphabet, Tamil (தமிழ), and Thai (ภาษไทย) (“Oh it bring back memories of spicy Siam. Words that are a great mystery to me and have looong word that become entire sentances.”). He’s extremely concerned (to the point of constant pop-up warnings) to let you know that it’s only guaranteed to work in Internet Explorer, but Firefox seems to be OK with it. (Via Mithridates.)