The photo sharing site, TwitPic, allows Twitter users to upload and share there photos directly on Twitter. Now the site will not post an image into Twitter, but an URL to the hosted image on TwitPic (unless you get their Twitpic Greasemonkey script). You can either upload the photos on the site, post them from any cell phone or use one of the many Twitter clients such as Twirl or Twitterrific.
Tip: You do get an individual profile page with an unique URL. While they nofollow the URL in your Twitter profile, they do provide a dofollow back to your Twitter profile.