Just to clarify before we kick off that this article is about research... but you also need to do preparation (competency answers, explaining everything on your CV, why you want the job, etc). Both are essential to be truly ready for an interview. I'll cover preparation in a future blog if it's of interest to you.
I'm going to have to start with the painful truth about conducting useful research for interviews... it's all about being organised and not just aimlessly surfing on the web (hands up who already knew this?...). We all do it (believe me, I procrastinate endlessly on Facebook/TSR/Twitter/Blogger/etc before I force myself to sit down and actually write these entries). You need to be really disciplined to really make the most of your valuable time. There is so much on the web these days that it is easy to waste a lot of time doing research for your interview without ever actually feeling like you are fully equipped. There is always the worry that something else obvious out there that you've missed that they will bring up at the interview.
The research approach you take will be slightly different depending on the industry and the company that you are applying to, but broadly speaking for "Top 100" type companies, there are 4 categories to consider:
4-the current landscape/news
Let's take them one at a time:
You need to understand everything that is already on the website about the programme or role that you are applying to. This shows your high level of interest, but more important allows you to speak intelligently with your interviewers about the programme and make the right statements about why it is right for you. As an interviewer, if someone asks you a question to which the answer is readily available on the site, it is very off-putting. So, devour the grad website - everything on it.
You need to understand the company structure - the different departments/divisions/areas (everyone calls them something different). Understand their global structure - where was the company founded (geographically) and what is their presence now. Understand their make-up - there have been a lot of major mergers and divestments in the last couple of years - make sure you are aware of any that have happened affecting the company.
Make sure you understand how they are performing and where the profit is being generated in the company. Have a look at the communications / investor relations / news sections of the site - be aware of what the company is saying to the market about themselves and their work. If applicable, take a look at the high Exec Summary of the annual report. This will usually outline where the company is at (although beware how long it has been since the report was released.... if it was 11months ago, the picture could be significantly different now).
Some of this information is quite 'fixed', so some people find it easier to read the information from a book, rather than the web (e.g. "All you need to know about the City" book). Research who their competitors are (and how they are performing relative to them.)
This is about demonstrating your knowledge of current affairs in the industry and that affect the industry. You also need to understand the current landscape of the industry - what is the current market for their products / offering? There is lots of readily-available information on this - blogs, Google News, the FT - but this is also one of the areas where it is easy to spend a lot of time surfing aimlessly. Try to undertake this type of research in careful 30min blocks. Pick a topic, and then research that and only that for that period. If something else springs to mind that you need to look into during that research, make a note on a piece of paper to add it to your plan, but don't go off on a tangent researching the new topic there and then (even if you think it might be more important.
Overall on this last one, it is not really something that you can research in a week before your interview - it is one that you need to be building your knowledge on over a period of weeks and months. Find the blogs / subscriptions that work for you and sign-up as soon as you can. RSS Feeds can also be useful from certain sites. It might even be worth setting up a separate email address rather than cluttering up your own personal address. Check out CNBC, MoneyWeek, Yahoo! Finance, hereisthecity, etc.
Keep all your notes well organised, and bookmark sites that you visit that are useful, storing them all in a folder.
I've put together a checklist for you if you are interviewing for an Investment Bank and are planning your research approach - it can be downloaded here. I'll try to put one together for Consulting too in the next few weeks - I've run out of time tonight - but it should not be that different to the IB one, just tailored slightly more towards that industry.
Above all, be organised and be disciplined with your time. Ultimately it's unlikely that you'll go into an interview feeling 100% confident that you have everything covered, but if you've covered a reasonable spread of research across the above topics, you should be able to talk to a good amount of what might come up.