If you don’t quite have the budget (or the desire) to completely re-tile or lay linoleum down on your bathroom floor, you can actually just use some screenprinted art paper and waterproof PVA.
If your bathroom is bland and ugly, you can spruce it up a bit without laying down tiles fairly easily. DIYer and designer Rachel just papered her floor with thick lining paper, some waterproof PVA, and then laid some screenprinted thick art paper with a nice design on top. She also put on a few more layers of waterproof PVA on top of that to protect it (she also suggests some boat varnish to keep it really waterproof).
It’s too early to say whether it’s durable enough for long-term usage, but it does look mighty good. If you’re not quite ready to overhaul your bathroom floor, for one reason or another, this is a pretty simple DIY solution that’ll keep it from looking like the the boiler room in your basement. Hit the link for more details.