Despite this fact, Google's Blogger users have absolutely no control on the filename of their blog posts. Blogger automatically derives the name from the title of the post - it just concatenates the first six words of the title separating each word with a hypen and also removes the common words like A or The.
For instance, if I create a new post titled "Yahoo! Desktop Search getting closer to X1", Blogger will store the file as yahoo-desktop-search-getting-closer-to.html. Notice that it even removed the exclaimation mark in the permalink.
Basic SEO understanding suggest that in the above case, the file name should contain keywords like "Yahoo", "Desktop Search", "X1" since the post is all about "Desktop Search" provided by Yahoo! and X1.
Since Blogger doesn't allow custom file names, here is a simple blogger hack:
1. Compose your Blogger article with a title containing all the keywords (6 is the limit) and in the right order (e.g. X1 Yahoo Desktop Search)
2. Publish your post on Blogger.
3. Now open the post in w.bloggar, an offline blog editing tool and change the page title to something more meaningful (e.g. Yahoo! Desktop Search getting closer to X1)
4. Click "Post & Publish". Congratulations! Your permalink filename is what you want it to be and no longer defined by Blogger.
There's another scenario - Say if you wrote a post on Monkeys an year ago and that article became very popular with lot of people linking to it. One day, you decide to add about Bananas in that same article so a page title "Monkeys and Bananas" makes more sense. But if you change the page title, Blogger will change your page URL or permalink - That would not be a good thing as people who have previously linked to that Monkeys page would no longer find it and there's little guarantee that search engines will index the new page. The above hack may save you here as well.