gistfile1.rb

#!/usr/bin/env ruby

require 'nokogiri'

doc = Nokogiri.HTML DATA
root_node = doc.at('font')
headline = doc.at('strong')
before = root_node.at('./text()[(following::br)]')
after = headline.at('./following::br/following::text()')

p before.text.strip #=> "Some foo bar text"
p headline.text.strip #=> "something"
p after.text.strip #=> "some other foo bar text"

__END__
<font size="2" face="Microsoft Sans Serif">
  Some foo bar text
  <br><br>
  <strong>something</strong>
  <br><br>
  some other foo bar text
</font>