Despite Livejournal beeing a free service, it allows you to post new messages to your blogs through external applications. This is much easier than having to log into their website and write the message from within your browser.
The only client I've tried so far is Drivel. It integrates perfectly within the GNOME desktop, and is very easy to use.
Once started, it logs you into the service and a window appears ready to post a new message into your blog. Other features include the ability to see all your previous messages and edit them interactively. I guess other clients may have more features (like backing up your messages), but I'm using this one mainly because it's designed for GNOME and is free software.
I would like to thank the author, Todd Kulesza, for his quick handling of bug reports and for kindly helping me to solve some problems that only appeared under NetBSD ;)