Most of us have multiple gmail ids as we want separate gmail account for freelance or work and a personal account to chat with friends.
To access these accounts at the same time we have to either open them in separate browsers like one account in google chrome and other one in mozilla or the other solution is to use meebo.
If you are working on windows then there is a small trick to logging multiple accounts at same time using Google Gtalk.
Just you have to right click on the gtalk shortcut go to properties, You will see window like this
You have to add -nomutex at the end of target.
Just Click Apply and Ok.
Just double click on gtalk and open as many as gtalk windows you want.