There are a number of Sri Lankan recipe sites. The ones below are recommended.

Asia Recipe.Com. Not a lot of recipes but what's there is good and I like the glossary of Indian ingredients giving English equivalents

Malini's Kitchen. A terrific contributor driven recipe site.

My Sri Lanka. Online site for chef Peter Kuravita's SBS television program in Australia.

Sarogini's Sri Lanka Food.net
. A small set of good recipes from this Perth, Australia, based cook.

Sri Lanka: The Miracle. Freelance Larry Austin's site for all things Sri Lankan including recipes and restaurants in Sri Lanka.