If you already have an email address and do not want to get a new Gmail account, Google does provide an alternative signup web-form to get your free Google account utilizing your existing email id. One simply needs to use https://accounts.google.com/SignUpWithoutGmail and complete the signup process skipping the need of an Gmail account. The same can also be accessed using the "I prefer to use my current email address" option located just below the text-filed where it asks for Gmail ID in default Google signup form.