Web Development and Stuff

Sometimes it's necessary or maybe just handy to have multiple email adresses that belongs to one actual account — for example, when you have to register two user profiles on some website but do not want to create additional mail service account for just that ( most websites require unique email for each user and didn't allow to register more that one profile for same adress ). Of course it's possilbe to have two or more email accounts and set mail forwarding to main account for each of them, but why use somewhat difficult way if Gmail provides abiity to have multiple adresses for one account?..