Pop into your local comic book store, and there will be a selection of free ones from which you can take one away with you. This is an annual event on the first Saturday in May!
Not sure which books are in the offer, as I haven't been out to have a look yet! Will update later :-)
You can check to see if your local comic book store is participating by using this store finderhttp://www.freecomicbookday.com/fcbd_global.asp