If you want to describe a small amount of something, try modicum. If you have a modicum of interest in something, you are a little bit interested.
Modicum comes from the Latin modicus, for moderate, and modus, for measure. We often use it to mean "any at all," as if "If you had a modicum of sense (i.e. any sense at all), you'd be able to see that the pencil you've spent the last five minutes looking for is tucked behind your ear."