On my MacBook Pro, I use the iStat Pro widget. It's very reliable, so I think Bjango's iOS app would be too. It's 99 cents. It monitors data from computers too. I've never tried it but if I wanted to monitor my iPhone or iPad, it would be the first I would buy and try.
You're looking for something utterly pointless - the way RAM is used on the iPad is different from the desktop, so it should be nearly full almost all of the time. You'd be looking at numbers that look really bad but actually just indicate that everything's running normally.
Basically, just don't even think about it - it's managed automatically (and very well), there's nothing you need to do.
@psonice Actually the iPads ram is almost never full the 1gb is never full and hitting in the 900s. It's always in the 600 something around. My iPad 2 was always around the 300 mark when l killed background apps. Thanks for everyone that was helpful!