How can I automate orders from Lego Pick-a-Brick?
I believe that many AFOL user groups had previously been able to buy in bulk from LEGO, but I don't know if that's still an option with the release of pick-a-brick - however as Joubarc points out there are often limits on the number of different elements, as well as a group limit on the number of bricks. Couple that with the fact that the process often takes months to deliver, and it's not an easy option.

Another option would be to take it offline: the LEGO catalogue often lists Pick-a-Brick elements and has a postal order form, so you could format that up in your spreadsheet application of choice and mail it in.

Doing a quick snoop around the network traffic when adding items from Pick-a-Brick shows that currently it uses a fairly simple post to submit the details to the basket:

ba     0
bricks 4239601,1          &lt;- ElementId,quantity
cat    UK
id     4239601,1          &lt;- ElementId,quantity
sid    0.4886243118128015


So something could possibly be created, but as Joubarc points out, there's no guarantee that the site would continue this way.