The best thngs can actually be found in Akihabara in Tokyo. Try to make a detour if you can. Also, in Taipei, there are a lot of cool things because most of the stuff is made there or in Japan. HK doesn't make much except for money.
Cool stuff that HK does have though is bootleg software and VCD's and some DVDs.
Be careful of the computer stuff bought in HK, it might be cheaper in the USA. HK is cheap for things made in China, and clothes but not always cheapest for computer components.