Bzip may do yet better, though it will take longer. 7z may be worth a try too. You're getting into the range where you could just toss the whole thing up somewhere without much hassle. If you're not trying to make money, I'd just throw the whole data set out there on a torrent. Why take the time to write an access service when you don't even know what people are going to want to do with it? First thing a serious researcher is likely to do anyhow is just scrape the whole thing off your website, at much greater expense to you.