Have you tried using a Site/List template (STP file)? As long as the entire
content is less than 10MB, this would be superior to any of the methods
listed. All data  types, lookup lists, data, etc. are maintained. However, I
don't think that this method keeps the version history  of documents  either.

01. Choose "Modify Columns and Settings" from any Windows SharePoint
Services List or Library that you'd like to move
02. Choose "Save [List Type] as template" to create a temporary entry in the
Site Collection's List Template Gallery
03. Give the template a name, title, and description (be sure to include
content and be aware that item level  security is not maintained in a
template)
04. Go to the List Template Gallery in the Top-Level site  Admin
([site]/_catalogs/lt)
05. Click on the newly created  entry and save the STP file  to your hard
drive
06. Delete the temporary entry from the List Template Gallery
07. Go to the List Template Gallery in the Top-Level Site Admin of the Site
Collection you want to use the List
08. Choose "Upload Template" and browse to the STP file
09. Go to the target Site for your List
10. Create a new List based upon the template
11. Delete the temporary entry from the List Template Gallery
12. Delete the STP file

A similar procedure can be used for Site Templates using the Site Template
Gallery

For Lists

On Source Site, save the list as template (with include contents option).
This will result  in a file  that you can import into destination site.

Once imported, create a new list based upon that template that you have just
imported.

The new list will have all the structure  (pages, views, etc) and the
contents (list items).

At this point template has served it purpose and you can delete it on the
destination (and you should).


PS 1: I don't remember how it handles the list and item level
security/permission settings. if you test this approach then refresh me what
you found on its permission handling.

PS 2: This approach will not work  if you are working in SPS area  with
different template then what you have in source area.

Yes---

I have used this method and is simple and effective-- The only downside
is that all 'author and create/modify dates' are replaced with yourname
and current dts.

Is it true that the max size is 10MB??-- this could be an issue.

The limit is real.

The 'author and create/modify dates' will actually be those of the site
creator.

One follow-up question... is there a way to merge content?

Basically we have a situation where we had two sub-sites  for
portions of a project with a discussion board for each. We want to
combine the two sub-sites into a single site  and as a result  it
would be nice to merge content. Any ideas? (for lists  and docs
I've just done the cut'n'paste)

We have a similar issue with splitting sites  into multiple  sub-sites
but that is easier  since I can just have duplicate content  and then
delete the data  I don't want.