This user isn't updating his journal. Can I have the username?
No, LiveJournal does not delete accounts for inactivity. Even if the user doesn't appear to be making journal entries, this can be misleading; the user might be making Friends-Only posts, for instance, or simply use the account for reading friends' posts and commenting on them. Additionally, many people may find that they have to leave the Internet for a while, and may come back after that long time and want to begin keeping their journal again.
Even if LiveJournal did delete accounts for inactivity -- which there are no plans to do -- usernames are not available for re-use, nor can users currently change their usernames. So even if the journal were deleted, you wouldn't be able to claim the username or easily transfer over all of your entries.
If the name that you want to use has already been taken, try a variant (such as adding numbers, extra letters, or underscores), or select another username entirely.
(this addresses one of the more common Support requests. it will, obviously, need to be changed if the user rename function becomes available again. Chose "his" in the title because English has no acceptable gender-neutral singular pronoun, and using "their" as a substitute makes the hair on the back of my neck stand up.)
Comments? Thoughts? Rotten tomatoes?
[Edit: added "No" at the beginning at suggestion of gooner and braindrain]