ooh sorry i forgot to post
ok, instead of doing just crunches, lie on your back and bring your knee's up to your chest, then just raise your head and chest. in a crunch style, but because you have you legs up, it works different muscles.
lie on your back, and keeping your legs straight, lift them straight up into the air and lower them down slowly. then before your feet touch the floor, raise them up again.
on your front, leaning on your arms (elbow to wrist on floor), and on your tiptoes, keep that position for as long as you are able to.
for each one make sure you are tensing your tummy muscles.