Hello,
The vagina is a muscle and muscles are made to be excercised. So to increase muscle tone in the vagina there are a couple different things you can do.
As the others have mentioned kegal excercises are very important not only for the vaginal muscles but it will help to tighten things up so that you will not have a urine leakage problem ...like sometimes when a woman sneezes she may pee a bit or sneezes. Ben Wah Balls are also very good.
** The third thing that I would like to add is that when your husband is inside of you do those Kegal's! Squeeze that muscle as tight as you can, then repeat. When he is ready to ejaculate, again...Really squeeze those vaginal muscles as tight as you can. This makes his 'ending" even better!
If you are diligent in doing your Kegal's it will not take you very long at all to help tighten that Pelvic floor / Vagina. Kegal while doing dishes, while at a stop light, during commercials on TV, while brushing your teeth...and so on. if you get the Ben Wah Balls, Just start w/ the one which is all you will probably be able to do for now any way, and use them several timea a day. it really takes a lot of muscle tone to keep them up and in!
Take Care,
~Tonya
It is kind of an advanced kegal exercise, but have you thought about trying jade eggs or ben wa balls? If you are unfamiliar with them, here are a few links that will explain them & their use:
http://www.calmspirit.net/jade_pearls/jade-eggs.htm
http://www.healing-tao.com/tao-garden/universal/en/taoist-sexual-practice/
I have not personally tried them, but I have known women that swear by them. There are more affordable versions out there. Those sites just have good info.
Okay, so I won't say that Kegal is the only way... but, it's the only way that I know of. Another approach would be to have the vagina surgically tightened.