who can affect your credit report like putting negative things on your
report? and how?

You may already know that even a credit inquiry has a negative effect
on your credit report. So, when a person asks if they can run a credit
check, your credit will be negatively influenced.

kev314, I must say that's the first time I hear that a credit check
will negatively influence your credit report. Do you perhaps have any
sources supporting this?

Thanks!
gwagner-ga

I believe it's true that too many credit checks can cause problems.
Here are a few online mentions of this:

Extending permission for too many credit history checks can make you
look risky to a potential creditor. A high ranking, well paid
corporate officer found himself unable to secure a loan because he had
shopped around for lower rates to refinance his home. The many credit
checks on his report lowered his credit score. He was denied the loan.

http://www.ext.vt.edu/news/periodicals/fmu/1998-06/crdthist.html

And one final thing. When shopping for a bad credit home equity loan,
don't let prospective lenders run numerous credit checks on you.
Remember, one of the things that brings your FICO score down is "TOO
MANY CREDIT CHECKS".

http://www.home-equity-loan.ca/bad-credit-home-equity-loans.htm

But be careful, don't have too many credit checks run on you until
you've chosen the loan package you want. Too many credit checks can
diminish your credit score and ultimately hurt your ability to borrow
at a lower rate.

http://www.givingyouthekeys.com/buyers/loanappr.html

Here's an entire article about the phenomenon:

http://www.thekcrachannel.com/call3/1421459/detail.html

say if you owe me 10 bucks, can i do something to effect your credit?
or only certain bank can do it?

and when you refer to 'credit checks', does it include obtaining your credit report?

Obtaining a copy of your credit report after being denied ccredit does
not affect your rating.

I'd like to bring your attention to two questions previously answered
here at Google Answers:

http://answers.google.com/answers/main?cmd=threadview&id=118257
https://answers.google.com/answers/main?cmd=threadview&id=91254

~~Cynthia