How should one deal with fellow students constantly asking for notes? I'm an undergraduate student in the Netherlands, and as the title states, I'm encountering an annoying situation. How should one deal with the situation of constantly being asked for the notes of a lecture, summaries of book chapters, flash cards, etc by other, fellow-students? 

I do not mind to share my stuff with my study-group, because everyone is working hard in the group, and we all benefit from each other, however what I do mind, is strangers (from my course) approaching me for my work; it even went as far as people offering me money for summaries, and other work of mine. 
Also, I don't mind when someone approaches me asking for an explanation to something; I like to explain material to other people; since I benefit from that as well. I, and others, however feel that it would be unfair to give away the work, on which we worked on very hard, to someone who didn't do anything. 

I know it would be easy to just give in, and thus having dealt with the problem. I just fear that: 


The students will come back for more 
They will give me the guilt if they can't study with my notes and don't receive the grade they wanted 
It will go around and more and more people will come to ask 


So, how can one politely deal in such a situation? I do not want to appear as hubristic or miserly.
Giving course notes is probably ok, if you are happy to provide them as a one-off. 

If becomes a regular occurrence and the person has no very good reason to not take their own notes (disability or serious family constraints), I think it is perfectly reasonable not to be "their mule". Once is fine, twice is perhaps ok, three times is being exploited. You are not being rude by saying no. It is simply unfair to you for them to exploit you. Don't let them define what is acceptable middle ground, they clearly push the limits to their own advantage.

However, in my time some students produced LaTeXed versions of course notes for everybody to use. If that's what you want to do, it's your perfectly acceptable choice (but it would be a good idea to check with the lecturer - in my time, our lecturers were enthusiastically in favour of a student-typeset version of their lecture which could even serve as a basis of a book; these days, copyright issues may make some lecturers wary of agreeing to that, so - ask!).

Giving out homework is a strict no-no - it's an assessment offence (collusion), and plus, you do not really help them this way to learn.

Addendum: since you are worried that they blame you for later failure, if you give them out make a clear disclaimer that the notes are incomplete and inaccurate and you take no responsibility for their content.