[Washi]

I know that if the recipient is using Verizon, you can send e-mail to nnnnnnnnnn@vtext.com (where nnnnnnnnnn is the 10 digit phone number).

Other carriers should have a similar service.

[sionnsar]

I know that if the recipient is using Verizon, you can send e-mail to nnnnnnnnnn@vtext.com (where nnnnnnnnnn is the 10 digit phone number).
Other carriers should have a similar service.

T-Mobile does, and even allows you to set up an alias for the phone number.

[Gun142]

Site I use for email to text - http://www.livejournal.com/tools/textmessage.bml?mode=details

Has more info about number of characters for subject and message body.