You can easily send a text to someone using your email, but you have to know the cell phone carrier the person uses. The email address always is the phone number followed by the appropriate syntax by carrier.
3035555555@tmomail.net T-Mobile
3035555555@messaging.sprintpcs.com Sprint
3035555555@txt.att.net AT&T
3035555555@mobile.mycingular.com Cingular