Webware: Looking for simple completed task recording web service

Looking for simple completed task recording web service

I manage large paid search campaigns and am constantly making changes/updates to my keywords and ads. I like to record these changes so I can go back and see what I've done on a certain date and for a certain account or campaign. I am currently using Google Calendar to track this, although I'm sure it's not the best method. I add completed "tasks" (the name of each ad group or campaign, along with what was updated or changed) to the "all day" portion of the calendar to track what was done on which date. I have a Google calendar for each paid search account that I manage, so that allows me to effectively "tag" each entry at least in a generic way.

What I am looking for is a better way to keep track of the work I have done. I would love to find a good web service that would allow me to enter completed tasks that I could tag with as many tags as I like, and a date stamp with some kind of simple calendar filtering functionality so I could go back and look at what was done on a certain date. So really what I would love to find is a simple web service/app with a list that I can continually add items to, that automatically dates each item with the current date when it was entered (editable) and allows me to tag each item for future reference (displaying the tag cloud or tag list for easy access)

Has anyone come across this type of web service?