I use the following:

http://www.lunapic.com/editor/

Upload the "before" picture then click "click here to add more files" add "after" picture then change Anamate Images to Raw Collage Pictures. "Crop" entire combo and then right click and save to your hard drive.

I then use http://photobucket.com/ to host my picture and link it into my message.

great job!!!

Wow. Awesome job! Looking good in that dress!!

Thank you for the advice about the pictures. You look awesome, too! You are almost all the way to goal!

look at you!!! you must feel amazing. keep at it lady!!

WOOT! You look amazing!

whoop, whoop. doing great!!

You look fantastic! Congratulations!

congrats!!

omg look at your buff arms!! Michelle Obama status!! You look fantastic