One of my favorite crochet sites on the entire World Wide Web is Tamara Kelly's blog, Moogly (mooglyblog.com). She's a talented designer who is constantly releasing new free patterns. Her weekly newsletter is always fun. And--she's got a CAL (Crochet-A-Long) going every year that always has the most wonderful granny squares!
I may make them all, or I may not make every single one, or I may make more than one of the squares I like best. I follow to suit what I want to make, and at the end, the blanket I make from them is always fabulous! The patterns are free, and from experienced designers, so the results are always good.
One thing I especially like about CALs is that I can go back to previous years' CALs at any time, and include some of those squares, too.
My latest square is number 9, the Crossed Square (http://jessieathome.com/crossed-square/), designed by Jessie Rayot of Jessie At Home. It's not difficult, and it sure looks gorgeous! The only thing that makes it above a beginner's level is the front post stitch that creates the raised cross. And that's not difficult at all. It's just a triple crochet (tr) that's worked in the previous cross stitch of two rows before. You crochet around that stitch on the front of the square, so it's a front post tr (fptr) crochet.
And it looks like this! Fun!
Maybe I'll make a few more of this one, it's so fun!