Have you checked out Greg Tang's website?

You might know Greg Tang from his great math books like The Best of Times,  The Grapes of Math, or Math Potatoes.   Many of his books are included in our Math Reads sets that we received last year.  His books are great mentor texts for reading, writing, or math workshop!  He includes strategies to help the reader make sense of the numbers.

Whether you are familiar with his books or not, his website is a great resource for all grades!
On this site, he has activities that correlate with his books. (One of these could make a great minilesson.) He has a word problem generator which allows you to differentiate your problems depending on student needs.  In addition to those great features, the site also has some pretty awesome games.  These games are leveled and many can be used from K-5.  The games allow for practice on subitizing, coins, integers on a number line, and more.

I think this site deserves a look-see.  Let me know what you think!