email reminder app?

sorry..another app request.

since the email tone on the iphone is a pathetic little 'ding' (and I can't find a way of changing this)...is there an app that will remind me I have an email?

eg, I'm outside and I get an email, the tone is less than useful and I don't hear it. but the app will repeat again until I read the email?

I'm not going to make comparisons, but this was my fav app when I was using windows mobile...in fact I am seriously having trouble living without it.

thanks