This is a .gs (google script) file that will fetch an image from a url using I suppose some of the Google Services APIs, converts that object to a BLOB, then sends the image to the email specified with the images inline within the email (This is so freaking cool - I tested it myself ^_^)

convertURLImageToBLOBThenEmailItInline.gs

 // This code fetches the Google and YouTube logos, inlines them in an email
 // and sends the email
 function inlineImage() {
  // var googleLogoUrl = "http://www.google.com/intl/en_com/images/srpr/logo3w.png";
   var youtubeLogoUrl =
         "https://developers.google.com/youtube/images/YouTube_logo_standard_white.png";
   //var googleLogoBlob = UrlFetchApp
     //                     .fetch(googleLogoUrl)
       //                   .getBlob()
         //                 .setName("googleLogoBlob");
   var youtubeLogoBlob = UrlFetchApp
                           .fetch(youtubeLogoUrl)
                           .getBlob()
                           .setName("youtubeLogoBlob");
   MailApp.sendEmail({
     to: "[email protected]",
     subject: "Logos",
     htmlBody: "inline Google Logo<img src='cid:googleLogo'> images! <br>" +
               "inline YouTube Logo <img src='cid:youtubeLogo'>",
     inlineImages:
       {
         //googleLogo: googleLogoBlob,
         youtubeLogo: youtubeLogoBlob
       }
   });
 }