If you want to get lots of google hits – and if you want your blog to be cut from “a whole cloth”, it’s best for all three to be related to what you want to communicate to your readers and clients.
Here are some examples:
http://www.boingboing.net/
BoingBoing
A directory of wonderful things
Comment: URL and blog name are the same (an ideal situation). While the name doesn’t communicate much directly, it raises curiosity – which is then answered by the tag line: “A directory of wonderful things.” This is a so-called A-list blog, one of the most successful blogs on the web.
http://miketodd.typepad.com/
“Waving or drowning?”
To explore and communicate radical faith and connect a community of apprentices
Comment: URL is the blogger’s name – not a bad idea: often the blogger’s name is better known than the blog or company name. Again, the blog name brings up an intriguing question and also perhaps a connotation – could this be a blog that deals with philosophical topics? And indeed, that is the case when you look at the tagline. The tagline also immediately announces that this is meant to be an interactive blog.
http://mylifeasareluctanthousewife.blogspot.com/
My Life As A Reluctant Housewife
Gabriella True is the quintessential Mom of twins who wishes she could snap her fingers like the “Practically Perfect in Everyway” Mary Poppins. Join this Reluctant Housewife in her passion for writing recipes, motherhood, shopping, reading, entertaining, and the history of holidays
Comment: Again, URL and blog name are the same. A very long tag line that speaks to a specific audience and tells the reader exactly what to expect.