I find myself going to Domain Tools for this data all the time. But I never want to pay them anything, and they only give you a few sites for free. They do give you server location info for free, which I am also always looking up, but it sits on another page in their site.
So what I did is I took a byproduct of the Parked Domains Project, i.e. IP address <-> domain name linkages, and I sorted by IP address. I also added more value by including server location as well as whether the underlying domains are parked, non-parked, or don't have a live site behind them.
I did put up a cutoff of 100 domains per IP address because some domains have literally tens of thousands. However, this is a vast improvement from the 3 you get at Domain Tools and has proven to be more than enough for my purposes.
I have coverage right now for these TLDs: .com, .biz, .org, .us, .info, .coop, .aero, mobi and .net. This gets you most domains, but obviously the vast majority of TLDs (mostly countries) are not covered. The problem is I don't have good domain lists for these TLDs. If you do, e.g. for .uk, .au, etc., and you would like to share them with me, I would greatly appreciate it. Also, if you have any feature requests, I will surely consider them.
