How do I extend User Profiles to allow multiple entries

seems to me you want to create views (lists of data) and with the content profile.module list those views in the panels provided.

You can get to what you are looking for by creating a view and then embedding that view in a block that you only show on the user pages.

1. You create the view including the fields that you want to display. Do all of this under Defaults, we don't need to add a display for this.
2. Create an argument User:UID, under Action to take if argument is not present: select Provide default argument then under Default argument type: select User ID from URL, and save that argument.
3. Create a new filter Node: Type and equal it to whichever custom node type you created to represent education information.
4. Save this view and remember the name, lets assume you named it something like Education
5. Go to Administer -> Blocks -> Add Block
6. Under Block description: add whatever desc. you would like, the same for Block title: just keep in mind this will be the title that the users will see above the view data. (Unless you theme it to look different obviously)
7. Under Block body: you want to click on Input format and select PHP code
8. Then in the Block body text box enter the following code:
   

   <?php
   print( views_embed_view('Education') );
   ?>
   

   *Note replace 'Education' with whatever you named the view when it was created.

9. Now drop down to Page specific visibility settings and under Show block on specific pages: select Show on only the listed pages. then in the Pages: text box type user/* , this will make it so this block will only show up on the user profile pages. Then click Save Block
10. Go back to Administer -> Blocks and look for your block under Disabled, in the drop down menu select content then click the Save blocks button.
11. Now create some of your education content types under a user account and then view that user profile. You should see them all listed under that user profile

What I would do is use contemplate module and the prepopulate module.

Using contemplate, add a link onto the Profile that says "Enter you Education Information"

When a user clicks this, it takes them to a new education node and automatically creates a node reference back to profile. You can do this using prepopulate module or the nodereference_url widget. The new node will have a node reference back to the user profile, call it "User". Then the new node will also have all of the fields you list above that the user can complete.

Using the nodereferrer module, you can then insert a view of a users educational achievments into the profile. Or, you could even have a block that comes up when you view the user profile.. that would be cool.

Other options you could use if you don't want to use contemplate and prepopulate include node reference Popup add and reference (http://drupal.org/project/popups_reference)