A lot of people probably know this, but I’m sure a lot don’t. The not-so-secret secret is that most wireless providers assign their subscribers an email address based on their phone number. If you send an email to that address, it’ll get delivered as a text message—if you attach a photo to that message—say, using the phone’s built-in photo app—it’ll get delivered as a picture message. The trick is just knowing the address of the contact you want to send the message to. Here’s a list of the most common providers. (xxxxxxxxxx of course is where you put the recipients mobile phone number [no dashes])

Alltel = xxxxxxxxxx@message.alltel.com
AT&T = xxxxxxxxxx@mms.att.net
Boost Mobile = xxxxxxxxxx@myboostmobile.com
Cingular (AT&T) = xxxxxxxxxx@mms.mycingular.com
Sprint = xxxxxxxxxx@messaging.sprintpcs.com
T-Mobile = xxxxxxxxxx@tmomail.net
US Cellular = xxxxxxxxxx@mms.uscc.net
Verizon Wireless = xxxxxxxxxx@vzwpix.com
Virgin Mobile = xxxxxxxxxx@vmobl.com