I'm living in a house with 3 other college girls. We share a wireless router. Can the network administrator (my room mate) monitor what I do online?

Yes. Network tools are relatively easy to use and can look at any aspect of network traffic. However, the question is, is your roommate savvy enough to know how to use them or is she just "administrator" because she knows the account password?

If you're paranoid about it, you can set up a virtual private network, use SSL, and in general encrypt your sessions and traffic. It will still go through the router but, even if she can "break in", it will be much more work.

Yes, and so can others who may be sufficiently motivated to invade what you think of as your privacy. See Footnote.

Bottom line: If you are concerned about privacy, then for goodness sake, don't broadcast your secrets on the internet. Especially wireless connections.

Regards,

Dave


Footnote:
"Privacy is an illusion; get over it!"
---Larry Ellison