It’s been a busy week for the iPad.

It started off with a bang, as Apple (AAPL) racked up pre-orders at the rate of more than 25,000 units per hour early Friday March 12, according to the team tracking order numbers at Investor Village’s AAPL Sanity board.

By Sunday, the initial frenzy had cooled. The pre-order rate slowed to 30,000 units per day on Monday, 10,000 on Wednesday and 5,000 on Thursday.

Total pre-orders for the week: 190,000 units according to Daniel Tello, who’s been manning the spreadsheet for AAPL Sanity. (See his chart below.) That doesn’t include bulk orders by institutions or reservations for store pickup, which the Boy Genius reports were pouring in that first weekend at the same rate as pre-orders.

“Based on this,” writes Deagol, “and using my intuition and experience, and voodoo or however you want to call it, I’m sticking to my prediction of 1 million sold by mid-April.

That’s considerably less than the estimate of 1 to 2 million units by April 3, which an anonymous analyst had offered TheStreet (perhaps set the stock up for a fall?)

But it’s not bad for a product few customers have set eyes on, never mind held in their hands.

Meanwhile, in other iPad news:

• Apple this week began promoting iPad bundles for educational institutions, offering a $20 discount per unit when purchased in packs of 10. See MacRumors here. That suggests Apple has either solved the rumored production problems or orders are coming a bit slower than it hoped. Either way, it seems to think it will have plenty of iPads in stock come April 3.
• Apple has opened the App Store to iPad developers while keeping them on the same short leash it used on iPhone developers. “Your opportunity to be part of the grand opening begins today,” reads the invitation e-mailed to registered developers. “Submit your iPad app now for an initial review by the App Review Team and receive feedback on its readiness for the grand opening.”

Below: Tello’s chart of cumulative iPad pre-orders for the first seven days.

Note: Unit numbers are calculated by subtracting average daily non-iPad orders and multiplying the difference by the average number of iPads per order. For more on Tello’s methodology, see his blog, Deagol’s AAPL Model.

Tello and his colleagues continue to track iPad pre-orders. If you want to contribute to their spreadsheet, send the data to ipadsales10@gmail.com. Include your order number with the last three digits Xed out, the number of iPads you ordered, the order time, time zone, memory capacity and whether your iPad is Wi-Fi only or Wi-Fi + 3G.

See also:

• iPad pre-orders: 10,000 per day
• Apple orders drop sharply
• Day 1 estimate: 120,000 iPad sales
• Apple sells 50,000 iPads in two hours
• The wild iPad Ruckus begins
• How many iPads will Apple sell?

[Follow Philip Elmer-DeWitt on Twitter @philiped]