At times I have thought it would be nice if I didn't have to even see some users posts. I thought the only comments made were negative, or just so far off topic like in the "ADS" thread that it seems like a waste of time. So, after asking and checking it is really a simple process.
Go to your user name in the upper right and click on it.
Select "Manage Ignore Prefs"
Search for the member name in the white "Member's Name" search box
Click, or un-click to change, if you want to ignore Posts, Signature, Messages
You will then be able to see a list of everyone you have selected in the past, and can easily make changes to what you are following from them.
When the user posts in a thread you are reading you will get a message asking if you want to see the user's post anyway, even if you are ignoring them. I find this useful in threads I have started, as I can then not see the off topic, extraneous, or even at times just negative remarks about something I am excited about.
Hope this helps some folks, and I totally understand if you choose to start ignoring me!