This is the current Baby Blanket I am working on. The pattern is from Jan Eaton's excellent book 200 Crochet Blocks for Blankets, Throws and Afghans.
I use Sirdar Snuggly DK. I get 5 squares from each 50g ball. How many balls I use depends on how big I want the finished blanket to be; cot size is generally 4 squares by 5. I'm doing this blanket 4 by 4 and have 3 more squares to complete. I join them together in rows.
I'm not 100% happy with the joining method I've used (double crochet with right sides together) as the joins look ugly. I'll try something different next time.