Before I put any sort of flooring on my concrete basement floor, should I put some sort of sealer or waterproofing solution on the basement floor itself? If so, what is recommended?

No. Clean the floor good. If your putting carpet down, which I do not suggest you can paint it with an apoxy paint to cut down on any dusting the cement will produce. If you planning any other floor the best thing is raw cement to allow the bonding materail to adhere better.

If you have concerns about dampness, you should be looking at water-proofing before you spend a lot of cash putting a floor down. Otherwise you will be tearing it up to remove any mold that will develop.

Damp proofing is only a short term patch. Not a cure.

Look at your history - it is probably too short though.

Anytime you but anything on a floor (coating, adhesive, tile, etc.), you change what is happening and the natural absorption/evaporation. This can have long term effects.

If you have feel you will have problems with the slab, do not rely on "band-aids" applied to the interior or exterior of the basement. It is easy to fall into the trap of patching one leak and then finding the next one. - Get rid of the water first or at least minimize it before you start finishing.

I was planning on putting laminate down. I have to check the levelness of the floor, which probably isn't that great so I might have to resort to carpet or a self leveling concrete.

The slab is in pretty good shape. I was just wanting some additional "protection" that a floor sealer or waterproofing solution might give

Duct tape a 3'x3' piece of 6 mil poly to the floor. After about 3 days, lift the plastic and have a look. If the concrete is damp, or if you find any moisture on the plastic, you will know what to expect. Any latent moisture in the concrete will lift an epoxy coating or become trapped under your laminate floor. Since any small amount of moisture present will evaporate into the air as it reaches the surface, it is hard to detect without creating a barrier.

Be very sure that the laminate your using is ok for below grade install. Many are not. I have torn many a floor out from basements because of trapped moisture below the plastic barrier people put down on the basement floor thinking their floor was dry.

Concretemasonry has some good points as well. Band-aids are not the way to do things right.

Be sure to do your homework on the floor you sellect.

What type of flooring for a basement would you recomend? I am not sure my floor is the most level so my choices might be limited

I do the very same thing that Maintenance 6 suggests on all my basement renovation projects. Any moisture trapped under the plastic tells me that there are water intrusion issues that need to be taken care of before any floors or walls are done.

If your using any laminate flooring in fact any floor other then carpet or smaller tiles it must be fairly level to be properly installed.
You need to go to a flooring store such as lumber liquidators and ask them what product(s) they have that would work for you. Otherwise you would be throwing money away.

Is a vapor barrier recommended under a laminate floor in the basement even though no moisture was detected from the "moisture test"? Would be hurt to put a sheet of plastic over the floor before the laminate goes down?