In this day and age, almost everybody has a good video card that can be used to crack passwords, like Nvidia and the CUDA framework, and it really helps to speed it up.
Yes, I agree that computing power is really helpful, but it cannot beat a good crafted custom wordlist. Cracking MD5 hashes may be fast, but try doing the same with other hashes :)
My advise is simple. Know your target as good as you can!! Their culture, their language, their people, what do they do for living, etc… and build a custom dictionary on top of that.
You may also find useful this old post published by the Pauldotcom crew. The idea behind it is using the target’s website for our dictionary since, in theory, it is a valuable source of the vocabulary being used inside the company.
I did some tests following the above commented tips and I used Cryptohaze Multiforcer (a CUDA based multihash cracker) to crack the passwords. The results were spectacular and I ended up with a 400MB wordlist (aprox 35M words) and it found many of the passwords in few minutes :)