The applications of scanning probe microscopy (SPM) to surface science are, of course, countless and have brought a real revolution to the field. Less expected but, a posteriori, equally logical is the revolution that single molecule experimentation (with both SPM and other probes) is bringing to the study of macromolecules of both biological and non-biological origin. On the other hand, in this journey towards single molecule studies it is actually at present possible to choose the size of the sample rather freely. Each size ( 1 or 1,000 or 1,000,000 molecules or even the bulk ) has its own advantages and drawbacks both experimentally and theoretically. After having given a couple of examples ( taken from the work of others ) of experiments on biomolecules at the single molecule level , I will show evidence from our own laboratory that working at the hundreds of molecules level, presents some unique advantages that make this type of experiments well worth pursuing. After having introduced the methods that give us the possibility to isolate a sample on the order of 100 to 1,000 molecules in the middle of a reference ( larger ) set of similar molecules, I will apply the time honored method of differential measurements to study the properties of monolayers of molecules of incresing complexity. Starting with saturated hydrocarbons and short strands of polyethylene glycol ( a molecule of great importance in the field of biocompatibility ) I will move to the study of small patches of DNA and some very recent results on proteins. The second class of results will be presented as an example of why quite a few people are presently convinced, that the field of "NanoBio" is not just a fad but may actually be our ticket to understand at least some of the complexities of a living cell.