Hi Huhu, I'm also facing a quite similar situation but I'm doing a MPhil, not a PhD. My supervisor is nice but he became very busy after he's been appointed as the VC of my university. Now he hardly finds time to read my chapters and papers that I write. So, I've found it quite difficult but at the same time found a few other ways that support my work.
(1) Comments form progress review panel - In my university PG students have progress reviews every six months. But if we work really hard and do more work within a short period, then we can request for a review even before its six months. I had my last progress review two weeks back and planning to arrange another by end Jan 2013. The comments given by the panel was very useful, specially because the supervisor is also there. Do you have that kind of structure in the place you do PhD? If so, try to speak to the panel members about your frustration at the review itself, then your supervisor will also realise that he has not helped you to overcome those frustrations.
(2) We have formed an informal research group with other researchers in the uni. We discuss our research when we meet. Content-wise, it does not give any support, as different researchers are in entirely different fields. Nevertheless, it provides kind of a 'clarity of mind' after 'purging out' everything you have in mind about your research. Occasionally we can learn from something another researcher has implemented.
(3) Try to speak to the supervisor and tell him that you really want to meet him. And then tell him all your frustrations. I once did this and my supervisor helped me a lot after that. (Now of course he's forgotten that so I think I have to do it again.) Perhaps you can do the same.
Best Wishes for your thesis writing...