The Highguard

Thalassian is a bit of a strange language to use, especially when people memorize phrases and don't use tongues! There are two really good resources for learning the language on an OOC basis, like saying "bal'a dash" on a whim to a friend (plus Tongues doesn't always work).

The Thalassian Thesaurus

Blizzard only gives us so much translated into common, and this resource is widely used with a HUGE vocabulary of Thalassian. Search and find!

WoWWiki's Thalassian Primer

A must-read for all elven roleplayers, this'll teach you the correct phrases for "hello", "goodbye", "How are you" etc.

In case anyone reading this is interested I can also link to the Orcish Primer which allows for even further IC-involvements for Cross-Faction RP, IC-Trades, etc.