Under OS X 10.5.4, if I try "ssh-keygen", I get a Bus error.

It will run if I "sudo ssh-keygen", but then all of my ssh commands require me to sudo to get them to run.

Any ideas?

That is strange. Are you doing it from within your home path when in the Terminal?

Yes - here's a cut/paste:

imac:~ djames$ pwd
/Users/djames
imac:~ djames$ ssh-keygen
Bus error

imac:~ djames$ sudo ssh-keygen
Password:
Generating public/private rsa key pair.
Enter file in which to save the key (/var/root/.ssh/id_rsa):

And regardless if I accept that file location or direct it to ~/.ssh/id_rsa, it creates a key I cannot use without sudo (and that has root as the username).

I do not have this problem on my macbook, which is at same OS version/build.

Finally hit on the right combination to Google an answer! This is a problem caused by an older version of a component (Instant HiJack) of Audio HiJack. Removed the component, and I am back in business!

http://thebigdeal.wordpress.com/2008/04/18/mac-os-x-ssh-bus-error/

Check permissions on ~/.ssh.
ls -ld ~/.ssh
and maybe, if there is already a file present that you don't have permission to override.
ls -lr ~/.ssh

Turns out it was a problem with an old version of Instant Hijack (a component of the Audio Hijack application). It was doing some "bad" kernel patching. I tried to post this before with a link to the article where I found the answer, but that post went into "waiting for approval"-land, so I'm leaving the link out this time in hopes that it will post. Google "ssh-keygen bus error audio hijack" to find the articles...