So, Google has introduced a feature using which you can sign in with two different google accounts on the same browser. Imagine not having to install another browser just because you need to login to work email which is managed by google apps' email solution! Well, to be honest, I would recommend having more than one browser in your system; but if you cannot be bothered, you do not need to logout of your account; pop in to another account, take a quick look and then come back to your main account again.
This is how you do it.
1) Go to your Google Accounts page.
2) Look for the option "multiple sign-in" in personal settings. If it isn't there yet, your account will probably be enabled shortly.
3) Click on the "Change" link. Now, you will see a message that this is an advanced feature that works for Gmail, Google Calendar, Google Sites, Google Reader, Google Voice, App Engine and Google Code.
4) Enable the feature. Click the button that says "On - Use multiple Google Accounts in the same web browser.
5) Note that your default account becomes the first account that you sign in to. This means that when you sign into non-Google products unable to support Multiple Accounts, that your sign-in will be done via your default account.
Note that this feature is easier than using Google Chrome's incognito mode or IE8's "new session" feature. Signing out of any Google product while in Multiple Sign In will sign you out of all accounts.