The apostrophe is your friend. It's wise to treat it kindly.
By all means, take your apostrophe to retro '80s parties. Just please don't invite it to those lame 80's ones. Share your DVDs with your apostrophe, but under no circumstances should you attempt to share your DVD's. The last time I checked, the DVD didn't own anything (and if it did, this would necessitate a whole new dimension of human rights discourse).* Would you say the same of Blu-rays? No, please don't tell me you would. "Blu-ray's on sale" certainly makes sense if you're talking about an old hick by the name of Blu-ray who happens to be going cheap. Otherwise, keep the apostrophe out of it. Seriously, just because you see the apostrophe in bed with the letter 's' in other situations (especially the 'X is' contraction), this doesn't mean you can generalise and go around thinking it's a universal, monogamous relationship. It most certainly doesn't apply to plurals. In fact, your friend the apostrophe is allergic to plurals in all but the narrowest of situations.