If you have a PC and want to write offline and then upload, Windows Live Writer is your option. It is actually a very powerful (free) tool for blogging. Here's a blog post about why Scott Hanselman uses this app for his blogging. I've used it off and on but am using it even more now that I have a Surface Pro. I used to draft on my ipad in Blogsy but the biggest issue I had was adding links and full compatibility with wordpress - I can do it all on my Surface Pro using Windows Live Writer. This post links to the app and the why-to from this blogger. It works with wordpress, blogger, and more.