Sure it’s super easy to change light fixtures, but sometimes you just can’t. If your space is really temporary, like a dorm room or a short term let, or even if you don’t have access to switch off the electricity then a refit is out of the question.
Here’s a few ways to deal with oogly light fixtures that won’t lose you your deposit.

1. Chic Scarf
A student classic that can actually work really well. The old scarf-over-the-lamp trick:

Of course you’d make sure that the fabric wasn’t touching the (energy saving) light bulb. ’cause you’re smart. Cheers to bhg for the image
2. Ooh La La Lacy

This is a bit of lace trimming taped in place with masking tape. The effect is really quite pretty when it’s dark too.
3. A chopping Board?

This is a flexible chopping board from Ikea with a hole poked in it. It completely replaces the glass bit, and it’s all heat resistant too so, bonus. I would have covered up the brass circle bit with electrical tape, maybe in black, maybe in a rectangle shape but we’re run out of electrical tape. Bloomin’ Mondrian
4. Holy Plastic Basket Batman!

This is a plastic basket (from the dollar store) with the handles chopped off and a big X shape cut in the base. The Big X shape allows it to be slotted over the light fixture itself. Let me know if you’re all ‘HUH?’ about this one. I have some more pictures.
5. Scandinavian Style

This is just paper, cut to have a kind of Scandinavian vibe and then taped into place. I got the idea from here.
All those idea’s range between the cheap and the free, If you’ve got a little cash to throw at the problem here are some other options:
6. Tord Boontje $65 = ooooooooooh PRETTY
7. Adagio Light Cover $157

Wait, $157, really? Well it’s not for sale anymore, so this HAS to be DIY-able… I’m thinking wire coat hangers and fabric… hmmm.
And finally, the big slice of gorgeous that got me thinking about all this in the first place:
8. Caro.Duke’s Umbrella Turned Light Fixture

So Pretty. SOOO clever.
Actually I like the original square light fixture except for the big round thing in the middle. I think that round part that twists on could be replaced with a smaller piece – all the ones I have seen are very small.