Is it possible to host a website for example in Amazon Cloud and have my domain point there, but have the same domain installed with Gmail for mail support?
As Eisb said in the comment the short answer is yes. For more detail keep reading.
Assuming you want to (or already) use the Google Apps email service you can point your MX records in your DNS configuration panel to Google servers, BUT your naked domain or WWW sub-domain to wherever you are hosting your webpage. To accomplish this you must have access to your domain configuration panel available in your Domain Name Registrar (Go Daddy or the like).
Suggested reading (wikipedia a good and easy to understand source):
Plus the Google Apps forums and tutorials.
google apps: www.google.com/a/