There is for sure. There are few other sites which are dedicated entirely for serious sinhalese, tamil and english poetry. But the following two are my favorites.
1.
http://sharepoetry.com - This is an international site dedicated for english poets. (there are many Asians too in the site with beautiful creations)
2.
http://www.kaviarana.net - This is a SL site, dedicated for Sinhalese and English poetry.
There are few others, I will drop them when I get hold of them