I want to grant the 'write' right to one user so they can delete log files in a given directory. These are http log files, so a new one is created each day. The file owner is 'nobody'. If I use the command 'chmod a=rwx *' will this work for the new files created each day.

I've tried the command 'chmod username+rwx *' and I get an error message that reads chmod: ERROR: invalid mode.

your syntax is incorrect. proper usage of the chmod command is:
chmod [+/-]drwx file or directory name


what it seems you want however, is to add that user to a group that has the rights to edit these files.
so, say you have a file access_log, this file has the premissions set to: -rw-r--r--
the owner of this file is nobody, and lets just say the group is httpd. so you could chmod +w access_log to add write privelages to users in the group assigned to that file. then you add your user to that group, httpd.

Actually to delete a file, you need write permission to the directory. rm gives you an error if you try to delete a file that can't write. But "rm -f" forces the issue.

But if you can't write to the directory, there is no way. The kernel enforces that.

ok, i need help creating the group and adding the user to the group. i'm using solaris 5.6, my aix man page says to use the command 'mkgroup'.
i've tried 'mkgroup' and 'mkgrp' solaris returns 'mkgrp or mkgroup not found'.

and, wouldn't you have to specify the group in the chmod command. my unix book has the example chmod g+x filename. i'm assuming you would replace filename with the directory name. if the group name is httpd would the command be chmod httpd+x directory name?

On solaris use groupadd.

The g is a constant. You don't replace it with the groupname.

chgrp httpd /some/directory
chmod g+w /some/directory

how to i add the user to the group?

I would just "vi /etc/group". But you can use:
usermod -G groupname username