After an initial flood of pent-up demand and some ups and downs over the first weekend, pre-orders for the iPad tablet computer are now averaging 10,000 per day, according to Daniel Tello, a Venezuelan blogger-analyst who writes about Apple (AAPL) using the pseudonym Deagol.

Tello has been tracking order numbers submitted by volunteers since March 12 at 8:30 a.m. ET, when Apple began taking pre-orders for the iPad.

By his calculations, which are based on a precise count of order numbers and an estimate of how many of them were non-iPad orders, Apple passed the 180,000 unit mark on Wednesday.

“I think sometime during Friday, perhaps before noon, the counter should roll to 200,000 units pre-ordered,” he told Fortune.

Tello’s tally does not include iPads reserved for pick-up at Apple retail stores on April 3, the day the device goes on sale. But according to the Boy Genius Report — citing its “Apple connects” — Apple’s 222 U.S. stores took an average of 700 reservations that first weekend, which would suggest that reservations and online orders are coming at roughly the same rate.

If true, the total number of iPads reserved or pre-ordered in the first week may be close to 400,000.

Published estimates of the number of iPads Apple will have manufactured by April range from a high of 1 million to a low of 300,000. Apple is still taking orders for the iPad, but spot shortages have started to appear in some iPad accessories, including the iPad case and the iPad keyboard dock.

Tello and his colleagues at Investor Village’s AAPL Sanity board continue to track iPad pre-orders. If you want to contribute to their spreadsheet, send your information 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:

• 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]