Wow, is this painful. Starting with my transition to Movable Type, I started using Textile, a Movable Type plugin that let you use text-based shortcuts for doing HTML markup. In the days before a rich text editor, this was a great time-saver.
A couple years later I switched to WordPress, but found a WordPress plugin that allowed me to continue to use these shortcuts. Not only did that mean that my past entries with the shortcuts included would still work, but it meant I could continue to use the same shortcuts - which I continued to do, even though WordPress had a decent rich-text editor.
(Can you guess where this is headed?)
Now that I'm converting to Blogger, I have around 4 years of posts that are largely useless when it comes to hyperlinks: insead of this, I have "this":http://www.google.com. With plugins installed in WordPress, it converts the short-hand to the proper HTML... but Blogger doesn't have any corresponding plugin.
So I've spent the last 2 days meticulously finding each hyperlink and updating it to the proper format. Not fun. Necessary, but not fun. I'll be done soon enough...