Y of x reminded me about one of my old favorite websites for math fact practice with a purpose:
5-10 minutes of daily practice will cement the math facts in your student’s mind, while at the same time doing a good deed. For each correct answer, a Free Rice sponsor donates a very small amount of rice to feed hungry people worldwide through the UN World Food Program.
Even very small amounts of rice add up. Since Free Rice started in 2007, its sponsors have bought more than 63 billion grains of rice, just by paying for one right answer click at a time.
You and your students can practice other topics as well:
More Online Math Fact Practice
A forum friend passed on the link to an online multiplication drill game that turned out to be perfect for Princess Kitten:
Kitten can target her practice on the hardest-to-remember facts, and the 5-minute timer provides just enough practice without wearing out her patience. She likes that the game shows a miniature times table and marks each fact as she answers it.
For younger children, try the Addition and Subtraction trainers. And while you are there, be sure to check out all the other great content on the Maths is Fun website.
Denise Gaskins' Let's Play Math 
Hello Denise, these are wonderful tools, thanks
Hi Denise.
In fact, to be sucessfull in maths, you must train every day. Congratulations for your blog.
http://learnstudymaths.blogspot.com/