Weaving in the ends is not so big a job as you seem to imagine. I have been a crocheter for quite a few years and have done more granny square afghans than I can remember (I give them as wedding gifts to friends, neices etc.) Anyway, the trick to it is to hold the end of the last colour along the edge as you crochet the next colour. This puts the 'end' underneath the stitches that you add, leave a bit longer tail and snip off later being assured that the "end" is well secured underneath those next round of stitches. Hope that makes sense - please try it. I know you will love to have made yourself a granny square afghan!

Don't they make wool that automatically knits into a striped sock? I've never understood how it works but I bet somebody (you???) could design a multi-coloured thread for crocheting granny squares.

I second what Susan said...crochet over the ends as you change to a new color - it works! I crochet over both ends(the one I changed from and the one I'm changing to) at the same time. Then the only end you have to worry about is the last color in the square. This might give you a better explanation. http://crochetme.com/tips/weave-ends-you-go

No, no, no. You can't give up that easily. Like the previous posters said, crochet over the old ends as you change color, then join squares on the last round. I know you wanted to have an on the go project so even if you only create and join 4 squares at a time to keep the project small you'll have considerably less ends to weave in. To join as you go just work a slip stitch to join the two squares on the last row.
Link for joining as you go:
http://www.crochetcabana.com/tutorials/joining_squares3.htm

What they said....crochet over the ends as you go along...it works great!

Interesting that I found your post today----I have been thinking of crocheting a lap blanket out of cotton. It sounds so nice for the summer. It will be ONE color, though---no weaving patience right now...

What a great idea to have a yarn that changes color for crochet. I just started doing crochet (is there a word, "crocheting"?) & now that I read the other comments - I may try a square using sock yarn.

Yes! Crochet over them! That square is too cute not to have many, many companions.

A yarn like that would definitively be a great idea, and I would be one of the first customers to buy
it :-)

I got my Interweave Crochet magazine today, and guess who was looking out at me! Hi, Alice! That was so cool.

Anyway, the magazine you're in has an article about joining as you go, and I'm doing grannies where I just crochet over the ends whenever I change colors, too. So... I'm with everyone else. Not going to let you quit. Nope, not going to.

I hate weaving ends in. But have started crochetting over the ends like others are mentioning. It's so, SO cute.

I have the same problem with knitting a blanket in blocks of different colours at the moment - even though I've been really careful as I go there are still little bits of wool that need to be stitched in with a wool needle :@(

I agree with crocheting over them. This is a technique that folks who do tapestry crochet do to "carry" the color not in use when doing tapestry work. Works great with granny square tails. When I teach someone how to do a granny square, I teach them how to do this, to avoid all the fuss with weaving in.

sometimes that's what swatching is for...
to let you know what you're getting into before you commit.

I'm a little late to this conversation, but oh well. Have you ever dyed your own yarn? It's not difficult if you use something like Kool-Aid or Wilton's Food Coloring. I'm thinking it would be pretty simple to dye your own yarn that changes color when you want it to. I've seen it done for socks, and can't imagine why it wouldn't work for a granny square. The key would be your guage. If you are using the same pattern with the same brand of yarn, you would have the best results. You would, of course, also have to get a large quantity of your yarn in white. Here's what I would do:

I would crochet the granny from start to finish, exactly like you would for the actual afghan, only using one strand of white all the way through. Don't weave in the final end. Now using your dye (whatever kind you use...I would think that the gel-type Wiltons would be excellent for this) carefully paint on colors where you want the color changes to be. You could even just alternate black and white on this one, since this will be your "template". When it's dried, frog the whole thing, and you have a length of yarn that you can use to show you where any color changes would need to go. So, you'd take another white lenght, and hold it parallel to the the template and dye the colors that you want. Does that make sense?

After writing all that, I'm thinking that if you were going to go through all that trouble, you'd probably be better off just crocheting them all in white and coloring them all in once they're done. Oh well, it was a good idea for a while. Maybe someone can take it and simplify it or something. Either way, good luck!