It depends on the target company, the domain of the team you are going to work with and the interviewer.
A-grade companies like Google, Apple, Microsoft etc.. expect problem solving skills. Basically, they see your IQ level. All you can do is warm up for the interview so you can showcase 100% of yourself. Learning new things doesn't really help here. These are the interviews you can't crack with mere preparation. If you have strong IQ levels and little bit of knowledge in Computer Science, say, time-complexity - algorithms, you can easily crack these interviews. But, if you are logically not that strong (medium or low), these interviews are not easily crackable. Basically, you have your fixed IQ level, which can't be improved in days or months- it is a matter of years or decades. What all you can do is solve some practice questions, so you will be warmed up to perform to your capabilities in the interview.
This website might be useful to you: http://www.careercup.com/
B leval comapanies, like Samsung, HP, IBM etc. might expect some knowledge (Domain knowledge, expertise in C/C++, SAP etc..) apart from the logical skills. The chances of cracking this interview is medium. Even if you are logically strong, sometimes, you might not be able to clear the interview because you might not have got a clue on some technical questions they ask, which they use day2day basis in the team.
C grade and lower grade comapnies, most of the times looks at what you know rather than what they want. These are the interviews which you can indirectly dictate the topics being discussed in the interview. That means, you can divert the interview towards the topic that you are more comfortable with. In my opinions, these are the interviews very easy to crack with some amout of preparation (study technical details - basics as well as some peculirities in the language. (eg. if you are a Java guy, apart from fundamentals, you should know some rarely used features too).
While a good interviewers always checks whether you can fit to the roles (they know how to validate you - they know what they want, so they see yourself in that role, asking some knowlege specific questions and logical (problem solving) questions.
It is difficult to classify startup, but they tend to behave like an A-grade company - so they might focus more on the logical skills (your IQ level :)
Consultancy companies, like TCS, Wipro, Infosys, Accenture etc.. are different in that, they might not know which team/project you are going to work - so, you need to have birds eye-view on most technologies and be expert in at least couple of them.