Collages vary enormously in quality, as you know. Most FK ones are simple photomontages; and most of those are quite amateurish. You might check out:

• Time Jordan's collages on her Immortal Beloveds faction site—sized a bit small for modern computers but still good, esp. (in my opinion) the one of Schanke


• Kristin Harris's wallpaper, which is indexed by character; I particularly like "Torn", "Desire", "Forbidden Fruit", and "Sister of Knight" (but you'll no doubt have your own preferences)