I have used : www.usenetserver.com before, speeds were great (maxed) and price was decent, a friend recommended it.
newsleecher <-- for the downloading
I used to use www.nzbsrus.com but it changed to a subscription based service but it did let you have 5 free nzb's..
Haven't used usenet for a long time tho, so all this info may be useless..
I'm sticking with torrents (until that stupid law comes into play) as they are quick and easy to find (TL for the win). Although my friend recently got a fine from a solicitor for using torrents, so i may change sooner rather than later..
Astraweb - No other providers come close. Basically giganews for a third of the price. Sab - Not bad, needs a better par program. Newzbin - Excellent site let down by not enough editors and shit retention. NZBMatrix - Bigger retention than newzbin but not as good overall, seems to rely on users submitting the NZBs, don't think it has a raw option? Still, £7 for a lifetime account is fucking nice ('til the site gets shut down)
scene = the good stuff that is released by evil 45 year old russian and albanian fat paedos to their gigabit topsites where it spreads to lesser sites where leechers up that shit to trackers/usenet.
Most of the stuff you download are probably scene releases, they are kind of the "official" releases and you usually know they are good because they are nuked otherwise.
New TV shows, documentaries, games or movies always have scene releases, but sometimes you want to download a rare app or something old that a random guy uploaded, for which you will need either Newzbin/Matrix or search through automatic indexing sites like Newzleech, which can be a bit painful.
I've got basically the same setup as Liam, but I use http://tvnzbrss.com/ to get TV shows automatically and I download documentaries and some other stuff from NZBs.org too.