Robes of Summer Flame

These are really striking leather robes from Magister's Terrace.  I've put together several different combinations of pieces to go with these robes.


Flaming Summer Thunderheart

Robes of Summer Flame Drops in Magister's Terrace
Circlet of the Starcaller Quest reward from Netherstorm
Thunderheart Spaulders Druid Tier 6
Manimal's Cinch Quest reward from Shadowmoon Valley
Thunderheart Bracers Druid Tier 6
Thunderheart Gloves Druid Tier 6
Enchanted Leather Sandals Drops in Hyjal Summit
Origin of Nightmares Drops in Naxx 25

Details here.

See Thunderheart Harness for the full set of matching Thunderheart pieces.


Gnarled Summer Flame

Soothsayer's Headdress Drops in Maraudon.  Murkblood Cover uses the same model and more muted, but similar, colors.
Gnarled Ironwood Pauldrons Purchase for Justice Points in Shattrath
Murkblood Bracers Green BOE
Murkblood Gloves Green BOE
Shadow Wing Focus Staff Drops in Blackwing Lair

Details here.

Summer Nightsong Flame

This is just the recolored Nightsong Garb, but with the Robes of Summer Flame substituted in for the chest.  All of the recolored Nightsong pieces drop in Ulduar.

Cover of the Keepers This model doesn't work in the model viewer, so I've included a screenshot of it instead.
Shoulderguards of Assimilation 
Bindings of the Depths
Handguards of Potent Cures
Boots of the Petrified Forest
Staff of the Plaguehound Drops in Naxx 10
 
Details here.

Another staff that could work with any of these sets is the Staff of the Plaguebeast, which also drops in Naxx 10.

All details here.

8/2/2012 Edit:

Here is the actual completed set on my Worgen.  It's a little different than what I have above.

Moonkin Headdress Quest reward from the Blood Furnace.  Same model and color as Murkblood Cover
The Dreamer's Shoulderpads Blue BOE.  Same color and model as the green BOE Wolf Rider's Shoulder Pads.
Robes of Summer Flame
Righteous Bracers These don't actually show, and that's the point.  Many other bracers would show above the Devilsaur Gauntlets.  Any small bracer that only covers the wrists and not the forearms would work here.  You won't need to transmog your bracers if you use the other gloves shown above.
Devilsaur Gauntlets Blue crafted BOE.  Same model and color as Murkblood Gloves and a couple of other gloves.
Manimal's Cinch Quest reward in Shadowmoon Valley.  Recolor of Stormrage Belt.
Staff of Earned Tranquility Low level Worgen-only quest reward.  This staff has an animation, with petals that slowly drop from the roses.  There is another Alliance-only quest reward with the same model, Chillwind Staff, but it has pink roses.

Details here.