There have been quite a few layouts in the history of Arwen-Undomiel.com. Unfortunately, several of the very old ones are lost, so there are descriptions of them instead.
This is one of the long lost layouts. Way back when A-U.com wasn't a dot com at all, and no one knew it existed, the site was hosted on Earthlink with a template layout. This layout had a black background with a gold diamond pattern down the left side, but other than that, there's no record.
Another lost layout. This one featured a simple banner with a closeup of Arwen's eyes from the Aragorn/Arwen scene in FotR. Below it was the navigation bar, which was flanked by purple animated stars. The main colors were either light blue or light purple (I can't remember).
The only change layout 2.0 underwent was that the main picture of Arwen would change every few weeks or so. The font used for both the top banner and the main picture was Fleurish Script.
Layout 3.0 featured pictures from the Aragorn/Arwen/Rivendell FotR scene. The font used was Fleurish Script.
Layout 3.1 featured a heavily-manipulated picture of Arwen in her blue/silver RotK dress and a FotR Lothlorien background. The main font used was Chancera, while the "version 3.1" font was SF Theramin Gothic.
Layout 3.2 featured pictures from Arwen's vision in RotK. The main font used was Edwardian Script, while the "version 3.2" font was SF Theramin Gothic.
Layout 3.3 features a picture of Arwen in her flight to the ford costume, with a FotR Rivendell background. The main fonts used are Beautiful ES and Beautiful Caps ES, while the "version 3.3" font is 04b21.
Layout 4.0 features a picture of Arwen from the "Arwen's Vision" scene, with a background picture of the arctic (sorry, not LotR :-\). The main font used is Splendid ES. The "version 4.0" font is 04b21, and the font used on the navigation (which was made using an imagemap) is Gilde.
Layout 4.1 is the first A-U layout since 3.0 to not feature a picture of Arwen prominently (w00t! after all, it's not an "Arwen site"). The main picture used is of Cascade Falls (photographed by dwvan10). It was made a little more "LotR-ish" by inserting a concept art piece of Aragorn and Arwen on the bridge in FotR. The main font used is Allegro. The "version 4.1" font is 04b21, and the font used on the navigation (which was made using an imagemap) is AGaramond.
Layout 4.2 is similar to layout 4.1 in that it does not feature Arwen prominently, but she's more noticeable in this layout than in the last. The picture of Arwen is from the Aragorn/Arwen dream sequence in TTT (although the floaty blue dress has been tinted green to match the background). The woodsy background is actually a compilation of three different pictures: from the two dark tree trunks in the middle to the left side is one picture, from the tree trunks to the right is another picture, and the waterfall is yet another image. The main font used was ALS Script, while the navigation bar font (an imagemap) is AGaramond and the "version 4.2" font is, as usual, 04b21. For the techies out there: Layout 4.2 is the first A-U layout to use PHP (by using an htaccess script, not changing the extensions of the pages), meaning that it is possible to change the layout of each page by just changing a separate navigation page instead of each page individually.
Layout 4.3 follows the pattern of the last two layouts by making Arwen not terribly prominent. This layout features the Lady of Rivendell reading outside in her blood-red gown from RotK, sitting on an Elven-styled bench (which some may recognize as nearly the same as Sam's outdoor bench in FotR). The main image used is not from LotR; it's just a random, autumny shot by wseahorse. The main font used was Cezanne with the capital letters being Freebooter, while the navigation bar font (an imagemap) is AGaramond and the "version 4.3" font is, as usual, 04b21.
Layout 4.4 features a wintery blue color scheme, the main picture of "Arwen" being a picture of actress Liv Tyler from her movie Onegin, although the picture was manipulated to look more elvish. The background picture is of Monte Bianco and was taken by giancardit. Overlaying the entire blend is an image of ice crystals taken by brainloc. The main font used was Champignon, while the navigation bar font (an imagemap) is AGaramond and the "version 4.3" font is, as usual, 04b21.
Layout 4.5 is a springy layout centered (metaphorically, not literally) around a manipulation of Aragorn and Arwen made from two images: the famous FotR giving-of-the-Evenstar scene (Aragorn), and a deleted scene in which Arwen talks to Elrond (Arwen, although her formerly purple dress has been given a green-yellow tint). The background is made from about four different pictures of forests. The main font used was Cezanne, while the navigation bar font (an imagemap) is AGaramond and the "version 4.3" font is, as usual, 04b21. The rather illegible text in the back is a combination of Elvish lyrics from Aniron, Evenstar, and Twilight & Shadow. On the forum, the font reading "Forum" is Zapfino Linotype Four.
Alternate description: Very pretty green layout. To which Even said Light, and tried to make Elva say Light too, but Elva went with Dark and Even got mad. And the rest of the modses were split between Dark and Light, which made things verily confuzzling. So then Arwen made it into a combination of both to make all her moddies happy. She hopes non-moddies will be happy too.
(Hey, what's life without a little insanity...)
Layout 4.6 is a wintery layout (we skipped summer since the spring layout was late, and fall because I was busy...sorry!) featuring a manipulation of actress Liv Tyler, turned into her character of Arwen. In the photo, she is wearing Arwen's light blue dress from the dream sequence in TTT, and she has been given a sparkling Celtic headdress and (of course) pointy ears. The background is of a snowy river scene, with icicles decorating the "roof" of the layout. The main font used was Mutlu, while the navigation bar font (an imagemap) is Aon Cari Celtic, with the background of the navigation being a sideways icicle, a sort of divider between the layout and the body of each page (inspired by Mugglenet). The "version 4.3" font is, as usual, 04b21. Changes from 4.5 to 4.6 include a lighter-colored scrollbar, different "Welcome to Arwen-Undomiel.com" sign, and slightly shinier (shiny! yay!) sidebars separating the body of the page from the blue background.