That's such a clever idea about the camera's for a gift, Peace!  I was going to also say to be weary of cameras for the guests to use, depending on what sort of crowd you'll have at your wedding.  I've known of kids to run off with most of the cameras and take fill them up with random shots of nothing, and of groups of half-cut lads to uh, add tons of photos of their own 'veges' (sans 'meat') to the films!  It depends so much on the crowd you've got there though.  Camera's on tables can be a lot of fun for your guests and could get you some candid shots, but if you're paying for the developing yourselves, could end up costing more for a lot of rubbish photos.  I really like that gift idea though. 

If you're looking to save money on catering (well, I guess it depends on how much you want to save), if you do the 'in lieu of prezzies please bring a plate' thing, it would pay to have a friend co-ordinate the menu and request say, so many meat dishes, so many desserts, etc, and even suggest good dishes to bring!  I went to a bring-a-plate wedding and was shocked at some of the basic and just nasty dishes that some people brought.  Pretty stink!  Or you could cater but do BYO alcohol.  Also, stuff like party favours for each guest can be really lovely but people will enjoy your wedding just as much without a little package of chockies by their place-name!  And instead of a band or DJ, having a computer full of MP3's hooked up to some decent speakers will give you tons of music to play, and means you can let guests choose tracks duke-box styles later on if they like.