Ted Nasmith has created A LOT of images for The Silmarillion. Some not even appearing within the pages of any illustrated edition. This post will serve as a reference on which publications contained which images.

~ 1998 illustrated hardback: [there was also a poster collection featuring 6 prints from this edition, which I've indicated here) ~
(front cover) Maglor casts a Silmaril into the Sea (also in poster collection)
The Sea
The Lamp of the Valar (also in poster collection)
At Lake Cuivienen
The Light of the Valinor on the Western Sea
Fingolfin Leads the host Across the Helcaraxre
The First Dawn of the Sun
Maedhros's Rescue From Thangorodrim
Eoel Welcomes Aredhel
Felagund Among Beor's Men
By Moonlight in Neldoreth Forest
Luthien Escapes Upon Huan
Morgoth Punishes Hurin
Turin and his band are led to Amon Rudh (also in poster collection)
Finduilas is Led past Turin at the Sack of Nargothrond (also in poster collection)
Ulmo Appears before Tuor
Earendil the Mariner
The Eagles of Manwe
The Ships of the Faithful (also in poster collection)
(back cover) Beren and Luthien are flown to safety) (also in poster collection)

~ 2000 Calendar, themed around the 1998 edition:

Beleg is Slain
Finduilas is Led Past Turin at The Sack of Nargrathrond
Tuor, Gelmir, and Arminas
Beren and Luthien are Flown to Safety
Maglor Casts a Silmaril
Fingon and Gothmog
Earendil Searches Tirion
Ulmo Appears Before Tuor
At Lake Cuivienen
Lamp of the Valar
The Incoming Sea at the Rainbow Cleft
Luthien Escapes the Treehouse
The Slaying of Glaurung


~ 2004 illustrated hardback: [ the 2009 Tolkien Calendar was 'themed' around this edition] ~

The Sea
The Lamp of the Valar
Aule Prepares to Destroy His Children
At Lake Cuivien
The Light of the Valinor on the Western Sea (2009 calendar)
The Ships of the Teleri Drawn by Swans
The Kinslaying of Alqualonde
Fingolfin Leads the Host Across the Helacraxe (2009 calendar)
The First Dawn of the Sun
The Burning of the Ships (also used on spine) (2009 calendar)
Maedhros' Rescue From Thangorodrim
The Gates of Sirion (2009 calendar)
Eol Welcomes Aredhel
Eol is Led to the Walls
Felagund among Beor's Men
Fingolfin's Wrath
The Orc-Host is Ambushe din Brethil (2009 calendar)
Tarn Aeluin
By Moonlight in Neldoreth Forest
Luthien Escapes Upon Huan (2009 calendar)
Transformd
Beren ad Luthien are Carried to Safety
Huan's Leap
Morgoth Punishes Hurin
The Hill of Slain (2009 calendar)
Saeros' Fatal Leap
Turin and His Band Are Led to Amon Rudh (2009 calendar)
Beleg is Slain
Turin Bears Gwindor to Safety
Finduilas is Led past Turin at the Sack of Nargothrond
Turin Reaches the Abandoned Homestead
Up the Rainy Stair (also used bas back cover) (2009 calendar)
Hurin Finds Morwen
Tuor Follows the Swans to Vinyamar (2009 calendar)
Ulmo Appears before Tuor
Tuor and Voronwe see Turin at the Pools of Ivrin (2009 calendar)
The Escape From Gondolin (Flight of the Doomed on Ted's website)
Maglor Casts a Silmaril into the Sea
Earendil the Mariner
White Shaps From Valinor (also used on front cover) (2009 calendar)
The eagles of Manwe
Tar-Miriel and the Great Wave
The Ships of the Faithful (2009 calendar)
The Forging of the One
The White Tree

~ 2008 illustrated paperback: ~

The Sea
The Light of the Valinor on the Western Sea
Fingolfin Leads the host Across the Helcaraxre
The Burning of the Ships
The Gates of Sirion
The Orc-Host is Ambushed in Brethil
By Moonlight in Neldoreth Forest (2009 calendar)
Luthien Escapes Upon Huan
The Hill of Slain
Turin and his band are led to Amon Rudh
Turin Reaches the Abandoned Homestead
Up the Rainy stair
Tuor Follows the swans to Vinyamar
Tuor and Voronwe see Turin at the Pools of Ivrin
White Ships to Valinor
The Ships of the Faithful (also used on front cover and spine)

~ Finally, these images haven't actually appeared in any illustrated edition (1998, 2004, or 2008): ~

Taniquetil
Luthien
Tuor Reaches the Hidden City of Gondolin
Morgoth and the High King of Noldor
Earendil Searches Tirion
Luthien Escapes the Treehouse
The Slaying of Glaurung
The Incoming Sea at the Rainbow Cleft
Fingon and Gothmog
Flight of the Doomed
Auel and the Seven Fathers
The Nauglamir
Tinuviel Reborn
Lake Helevorn
Aredhel, the White Lady
Tuor at Vinyamar