I love this crochet tissue box cover. It's so much nicer than the ugly cardstock one that lies underneath... I used four matching/contrasting colours: teal, purple, green and fuchsia. I used a 3.50mm crochet hook and worsted weight acrylic yarn (Wibra Saskia and Zeeman Royal).
If you want to make one of your own, you can find the tutorial right here: The Royal Sisters: Granny Tissue Box Cover. I really like her tutorials, very clear and easy to follow. I had to adjust the pattern a little bit so it would fit my box, since mine is a bit smaller than the one they use in the tutorial.