How to select articles by (author|subject|...)

[Lars Clausen <lrclause@cs.uiuc.edu>]

When going into large newsgroups or mail folders, I frequently need to just
find articles that are from a certain person or with a certain subject.  I
can't see any easy way to do this in Gnus.  I would expect
gnus-group-select-by-author or similar.  I have been perusing the info
pages and FAQs to no avail.  Is there a way to do this?

If not, how hard would it be to make Gnus do the following:

Allow entering a group showing only articles matching a certain regexp.

Interface with BBDB to get From: names and aliases.
  E.g. 
M-x gnus-group-select-some-articles
Select articles by (F)rom, (S)ubject, (D)ate, (R)egexp? F
Select articles from: Kai[TAB]
Select articles from: Kai Großjohann

Interface with a mail database of some kind (haven't started using any, as
I can't use it from Gnus yet).

Thanks,
-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| Hårdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
will defend to the death your right to say it."   | Where are we going, and
    --Evelyn Beatrice Hall paraphrasing Voltaire  | what's with the handbasket?