I came across this neat site for teaching Greek to kids today. Looks very do-able, and it is free until September 2010 as it is in process. However, it looks like it might be worth paying for...depending on what the cost will be.
**Interesting tidbit: "There are 5,437 different words in the New Testament. They occur a total of 138,162 times....319 words account for 110,425 word occurrences, or 79.92% of the total word count, almost four out of five....The point is that if you learn these 319 words well, you can read the bulk of the New Testament....Most introductory textbooks for other languages have about 2,000 words" (Basics of Biblical Greek Grammar, William D. Mounce, pg.18).
So you see, learning Biblical Greek is not nearly as hard as you might suppose. For example, learn the word "kai" which is the Greek word for "and" and you know 1 out of 10 words in the New Testament! Awesome stuff!!