I see that as a good work-around as mentioned by Chad, but I see one
problem each in the two suggestions:

1. By using the 'Check Out' feature, the document  will always be listed
as 'checked out to ...' status which would confuse the users whether the
document is the latest or is under modification by the owner who has
checked out.
2. Giving access to only one person  on a subsite would not enable others
to even view  the document.

What we need is a solution where the only owner of the document can
modify or delete the document whereas the other users can just view the
document or the owner should be able to specify certain user(s) who can
view the document.

This is actually an interesting topic for most of the document
management users.

Security is at the library level for document  libraries on a WSS site.
Therefore it is not possible to create  "different" security levels for
each document. The only way to allow read access for a user  is for that
user to be in a reader role and that role is for the complete doc
library. The only true way to allow users to have read only on a doc and
read/write on another doc is to have them in separate document libraries
with the user in the reader role in one and contributor in another.

this is a good idea. But, don't you think it would be a
good idea to give  full control only to the "document-owner" with same
library? I do not see a way for this solution. Anyways, your suggestion
should work out with some planning.

I agree and I would think I has always been high on the wish list. But
for now it is doc-level security

Maybe someone else out there has a better answer....

I am also new to SharePoint and have been trying to find out as much info as
possible on SharePoint Services and SharePoint Portal Server. Am I correct
in thinking that the only way to achieve single document  user rights  is to
buy the Portal Server?

You are incorrect - neither WSS or SPS includes single-document security. There
are some 3rd party tools that can add this however.

Am I correct in thinking that the only way to achieve single  document
user rights  is to buy the Portal Server?

No. SPS is based on Windows SharePoint Services. Neither support document
level access controls.

We're investigating the use of Windows Rights Management Services (RMS) but
don't have anything to report just yet. Full-text indexing is the one
capability the RMS-protected documents can't support (inside or outside of
SharePoint).

With 3 you get egg roll:: Server 2003, Office 2003, SPS 2003 = Windows
Rights Management Services(RMS)= single  document rights  control.
www.microsoft.com/.../default.m
spx

Do you know the names of those tools?

Are you saying that RMS Docs are full text indexed by SPS at
all? Meaning there is no way to give rights  to the content access
account to allow access to RMS docs?

I think the issue is more with security trimming for the users when executing a
search. Normally a user  is only shown results that they have access to - in the
IRM case the indexer is not IRM-aware so IRM rights  will not be taken into
account when displaying results.