This may actually be better in the applicant forum since I think there are a fair number of people who will be facing this. Of course you have the typical actions like going through monster.com and those types of sites. Then finding the major companies in the area who hire people with your significant others background and going to their sites routinely. I am sure we all know that a lot of jobs are only posted directly to company's own career website. At least you are being proactive and looking ahead of time. However, its still tough since companies prefer to hire local since they think its more likely they will attract you and also they wont have to pay to relocate you...this is what we ran into when my wife was searching.
OK now the unusual aspects of the MBA significant other job hunt...
First thing I would do is contact the school and ask if they provide any help with the job searches. Some schools have a person specifically there to help spouses find jobs. I know at Kellogg there is a woman who part of her job is to help connect significant others to people that may help find a job. They have been doing it for a long time so they probably know the best recruiters and also will have contacts in many other industries. This can be incredibly valuable, several of my wife's friends got this job way. The students and significant others you will meet are also a valuable resource that should be tapped.
Now something you may have to face that can be a challenge is why are you in the area. Lying is bad, and eventually people will find out the real reason you guys are in the area and you dont want make a bad impression. It may not come up but you will want to come up with your "story" ahead of time. I know people who framed it such that it makes it sound like you will be working for the school not attending it. Simplying saying, oh my wife/husband is starting at X University this fall. My wife I believe kind of framed that I was going to school but my career choices made Chicago the logical long term place we would be as long as things worked out well. She also choose a job with a company that has multiple locations so there is a chance she may be able to transfer to another locatoin if I end up at a job there when I graduate.
My wife attempted to look before we moved but found it difficult to make much headway. We arrived a month before school started and she really started looking at that point. She got interviews lined up, did phone interviews in August, then got called back for in person when we got back from KWEST and ended up getting mutliple offers a few weeks later.
Now the words of caution:
I know there are significant others here who still are looking and a few who lost their jobs alread. It really depends on the field you are in and its only gotten more difficult since October. My wife's company placed a hiring freeze in November and some of friends companies have too, and she also has friends who had offers that vanished. Some are just doing temp work and still looking for fulltime stuff. Hopefully, your significant others work in fields that still have jobs and not in those fields that have tons of available talent but few jobs. Depending on your situation, giving up a well paying job and moving with poor prospects might cause more stress than doing long distance for a few months. You also would have more money that way even if you are paying for lots of airplane tickets. Its a lot to ask someone to give up their life to move so you can attend school, if you add to that them being stuck at home looking for work while you are super busy at school it may be incredibly difficult.