Since everyone is so helpful here and learning lots (on my end).. I have just started to get the hang of the IPOD touch ... but I noticed .. regarding my email.... I have 2 set up which I read all the time....
but if I pass my TOUCH to my kids to play the games .. they have access to my email also .. how can I avoid them to read my emails while they use my TOUCH to play the game apps???
Unfortunately there isn't a simple way to do this. The passcode lock is designed to prevent anyone from using you iPod should it ever be stolen. It don't allow you to lock out apps.
There is only way I know to do this, but it can get annoying after a while. The same way you set up your accounts is how you control it.
On your iTouch, you do the following:
Go to SETTINGS.
then MAIL, CONTACTS, CALENDARS
Once you're in MCC, you will need to click on each individual account. In each account, you will need to turn the account off and possibly delete the password. First thing you can try to do is to simply turn the account off. If this works, then great.

This is the fast and easy way.
Sometimes simply turning off the account won't work though. If your kids really wanted to see your e-mails, all they would need to do is simply go into settings and turn the account back on. Don't put it past kids to know how to do this already or figure it out. If they figure it out, then you will need to also delete the password. They would need to know the password to turn the account back on. To do this, do as I mentioned above but also delete the password. To delete the password, click on the PASSWORD tab and just hit the backspace key until the password is deleted. Once you delete the password, click on DONE. Depending on your account settings, it will warn you that the server is not responding. Click OK. After you press OK, click on DONE again, It will ask you if you want to SAVE or EDIT the changes. SAVE the changes. At this point, your accounts should be disabled. If you click on the mail app, you should see the WELCOME TO MAIL screen to set up new accounts. If you get this, you did it right.
Now the annoying part to this is, you would need to do this each and every time. Once you are ready to check your e-mails, you would need to go back in, enter the password for each account and turn each account back on. Just follow the same steps to turn them back on. Only takes a minute or 2 once you get the hang of it. Just a pain to remember when you just want to go in and check your e-mails right away.
Hope this helps.