Okay I'll throw some out there:

Clearly it isn't your genre, but If you like some of the softer Nine Inch Nails tracks, check out the band Prick, and their self-titled album in 1995. It is highly regarded as one of the finest lesser-known albums of the 90's. Ever track is excellent. It is clear that Trent Reznor (who signed the band) was highly influenced by Kevin McMahon, the lyricist and vocalist. If you have trouble finding them on youtube, due to their name, try tagging tracks such as "Fair Fights" and "Animal". They'll pop right up so you can have a listen to judge if worth your time.

Ezio. They might be more up your alley. A folk band, some would say. Another great lesser-known band.. in USA and UK at least. They are from England yet are huge in Germany, I think. Predominantly two guys, acoustic guitars, fantastic lyrics, and their album "Black Boots on Latin Feet" is another no-bad-tracks album.

Marianne Keith. Had to throw her in here. Young girl from California, winning many awards, and has released several great albums. You can find her on the net. Check out the track "Make You Mine" for a good example. Poptastic, but the talented kind - great lyricist and vocalist.

Adele. I hate jazz, but this is different - easy listening enough to not qualify, and lets face it, she has one of the most flawless voices since Karen Carpenter. Check out her self-titled album. Possibly the best album of the past 10 years imo.

Since you have Neil Young on the list, don't forget his unplugged album. Epic.

Hmm... no R.E.M. on your list. That's a love-hate band if there ever was one. Such a huge library that there are bound to be a few tracks everyone likes if you can sit through the 16+ albums to fine them. Perfect Circle, or Long are lesser-known but worth a download.

Considering some of the artists you have listed, and their era, I'm surprised not to see Leonard Cohen at least get a mention.

I think there was a law introduced in 2000, that if you don't have any The Eagles albums in your collection, that the MPAA can fine you $1 per song. Don't quote me on that.

Oh, grab the studio version of Sweetest Girl, by Wyclef Jean and Niaa. Check out Niaa while you're at it. wow.

How about some Matchbox 20, mainly their debut album "Yourself or Someone Like You". Another no-bad-track album. Their roots, and their finest.

I'm not sure we can be friends if you don't download some Radiohead, be it Pablo Honey, the Bends, or later when they started getting... experimental/weird (OK Computer et al.).

If you don't download some Bob Marley, Evony Admin might force you to change your name. lolz Legends will do. Has most of his finest work.

Massive Attack or Portishead for some real chilled tunes. The M.A. track Teardrop should be in every collection, imo.

Find working class British accents funny? Check out "Original Pirate Material" album by The Streets. Won a bunch of awards, and rated one of the best albums of the year, but never made it huge outside of the UK. At the very least, it'll make you chuckle.

Tegan and Sara. Worth a listen... just to prove I do know some young music. Great voice, pretty unique. Good fun. lolz.

Other quick mentions/reminders - Queen (have to have some), Red Hot Chili Peppers, Cranberries (who doesn't love the Irish accent), Travis ("The Man Who" album), Coldplay, and Yeah Yeah Yeahs.