(from jewfaq.org)
Tu B'Shevat, the 15th day of the Jewish month of Shevat, is a holiday also known as the New Year for Trees. The word "Tu" is not really a word; it is the number 15 in Hebrew, as if you were to call the Fourth of July "Iv July" (IV being 4 in Roman numerals).
There are few customs or observances related to this holiday. One custom is to eat a new fruit on this day, or to eat from the Seven Species (shivat haminim) described in the Bible as being abundant in the land of Israel. The Shivat Haminim are: wheat, barley, grapes (vines), figs, pomegranates, olives and dates (honey) (Deut. 8:

. You can make a nice vegetarian pilaf from the shivat haminim: a bed of cooked bulgar wheat or wheat berries and barley, topped with figs, dates, raisins (grapes), and pomegranate seeds, served with a dressing of olive oil, balsamic vinegar (grapes) and pomegranate juice.
Some people plant trees on this day. In my childhood, Jewish children commonly went around collecting money to plant trees in Israel at this time of year.
In the 16th century, kabbalists, developed a seder ritual conceptually similar to the Pesach (Passover) seder, discussing the spiritual significance of fruits and of the shivat haminim. This custom spread primarily in Sephardic communities, but in recent years it has been getting more attention among Ashkenazim. Aish.com provides a traditional text for this seder. The Jewish college student organization Hillel also provides materials for a Tu B'Shevat seder.
(here is the link for the whole article:
http://www.jewfaq.org/holiday8.htm
here is another source of info:
http://www.chabad.org/library/article_cdo/aid/3264/jewish/Tu-BShevat.htm
Here is a recipe from food.com for a holiday dish:
7 Species Salad for Tu B'shevat
Here is a link to some tasty looking recipes for the holiday that have no added sugar and no flour!
http://www.chabad.org/library/article_cdo/aid/1397773/jewish/Tu-BShevat-Recipes.htm