It's possible that primordial black holes (PBH) formed out of the initial density perturbations set up by inflation. Black holes would result from regions in the universe with comparatively large overdensities (or comparatively small expansion rates). In most models, these black holes begin to form when the seed perturbation re-enters the horizon after inflation -- and so the mass of the black hole is characteristic of the size of particle horizon at that time. This gives a fairly wide range of possible black hole masses: those formed early (just after the Planck time) are just fractions of a gram, however, those formed later can be much larger (10^5 solar masses).
Light black holes (with masses less than 10^{15} grams) will have evaporated via Hawking radiation by the current epoch. However, those heavier guys may well still be around. So, finally getting to your question, I think yes, there has been some work done on determining whether primordial black holes might contribute (in part or in whole) to the dark matter density. Here are two references I fished off spires (I haven't looked them over closely, admittedly).
http://arxiv.org/abs/astro-ph/0302035"
http://arxiv.org/abs/1001.2308"
The claim that PBH's make up all the dark matter seems a little difficult to make work, since it's pretty clear that we need some form of weakly interacting dark matter to get structure formation to work right. But, perhaps they suggest a way around this in the paper...
