I began using the program for this purpose in 2009 and continued to in nearly all the colored charts in my color separations for knits posts since then. Gimp offers a whole other series of options for knitters in BW with magnification as seen in more recent posts here. I thought I would revisit some of the tutorials written by several other knitters prior to more posts of my own on using Numbers for anyone having Excel available to them. They are in no particular order. Marnie’s and Fleegle’s blogs offer tips, techniques, and how-tos in a series that I found extremely helpful when I began my own spreadsheet journey.
http://fibremuse.blogspot.com/2009/02/charting-patterns-with-excel-part-1.html
http://marniemaclean.com/blog/tutorials.html#.Um_-wpFQY7I
http://www.chemknits.com/2010/01/how-to-make-knitting-chart-in-excel_9394.html
http://fleeglesblog.blogspot.com/search?q=charting+with+excel
http://anniebeeknits.wordpress.com/2011/06/06/charting-in-excel/