Actually, BlueMix gives you 375 hours of 1 gigabyte units. If your web app is configured to use 0.5 gigs of RAM, then you get 2 * 375 hours free per month. I was running a node web app with a data store using a combined 0.25 gig units, so running that 24/7 would only use up half of the free monthly tier.

IBM is trying to buy there way into the market.