Is this any good? [http://www.btz.se/minis/DIY/48_crocheted_bedspread.php here]]? - it is in 1:48th scale, but perhaps you could adapt it by just making more squares, or using thicker yarn/biggerhook.
I've recently got a dollshouse (always wanted one - my sister got me one for my 53rd birthday ) and I've found quite a few patterns in books for miniature furnishings which I've borrowed from the library. Also the dollhouse magazines sometimes have a knitting or crochet patterns in them (but also quite a lot of guff, so worth a good look through before you buy)