Illumination is one of the most important factors in creating the ambiance of a space. In a basement it is even more important, because the rooms position recessed in the ground necessitates that its windows are set high in the wall. This makes it difficult foir natural sunlight to enter the space, because of the weird angle which it must attain in order to get through these specially positioned windows.
In an unfinished basement, this lack of light can actually be used to your advantage. Since the walls and features of the space will tend to be less attractive, you can hide these attributes in shadow, and choose to illuminate features that you prefer.
Novelty lighting has the ability to draw the eye towards itself, and away from everything else. In this way various novel illuminations can be used to create points of light, around which you can craft a makeshift room.
For instance, placing an illuminated Tiffany lamp on a pedestal in a pitch black basement creates a circle of light. Placing chairs, tables, and even other back up lamps around this space, allows you to carve a room into the dark. Couple this with accessories, rugs, vases, clocks etc. and you end up with a rather attractive room, devoid of walls, where you control what is seen and what is hidden.
Illuminated clocks are another form of novelty lighting which are especially useful in a basement. They can be hung on a wall to show off a single finished pane, or can be left as an accent ona table, or even hanging from the ceiling.
Another way to use novel lights throughout this space are to hang christmas string lights throughout areas you want to illuminates. They can be used to create pathways through the space by laying them on the floor, or if bunched together can hide unseamly cielings and walls. Globe lights have a similar, if less subtle effect.