Here’s an on-the-ground take from a source who I liked and trusted before he was working for one of the campaigns, and I still like and trust:

1. Romney clearly has the largest presence here. They are handing out the hideous yellow shirts to everyone who comes near their tent, and I saw quite a few folks with yellow shirts, and stickers for the other candidates. However, even if only 75% of the yellow-shirters are Romney folks, they outnumber everyone else. 2. The Huckabee contingent here is small… less than a third full. I saw *no* people walking around with Huckabee stuff outside the tent. I think his campaign ends this weekend. 3. The TGT [Tommy Thompson] tent is *dead.* Less than 100 people there when I walked by. I think we are also shed of TGT this weekend. 4. Tancredo’s tent is almost as big as Brownback’s, and almost as full. Of course, part of the equation involves busing people in and out, which [all campaigns] are doing a lot of – but judging on eyeball numbers alone, it’s between Brownback and Tancredo for second. 5. Ron Paul appears to have as many people here as Tancredo, but as has been noted elsehwere, there are serious doubts as to the number of people who are Iowans, and thus eligible to vote (you have to produce an Iowa driver’s license). Also, many of his supporters give, ah, the appearance of being radical college age liberals. Which confirms my thesis about them. 6. Duncan Hunter’s crowd appears to be somewhere between Huckabee and Tancredo. He’s promised to stay in the race until the end, though, so I don’t know what that’s worth. 7. John Cox is also here.

As I said, this individual is affiliated with one of the Ames-participating candidates, so feel free to take it with a grain of salt or whatever skepticism you deem necessary. Obviously, counting t-shirts and buttons is a subjective measuring stick. But a finish of Romney, Brownback/Tancredo, Paul, Hunter, Huckabee, Thompson and Cox in that order wouldn’t surprise many, other than Huckabee finishing lower than expected.

UPDATE: Another asssessment, from Chad:

I just read the Campaign Spot on crowd size, and would agree BB [Brownback] had a good crowd, as I had to get thru it to leave the grounds.
When I left at 2pm, there were many open parking spots around the stadium; I suspect many with families had left after voting and eating and going on a ride down the slide–keep in mind it is hot as hell out there–I saw a lot of tired kids.
So crowd size is hard to judge with people coming and going, but early on Tommy had a good crowd (around 11am). I did not see Tancredo’s up close, Huck’s was OK, but poor Duncan never had more than a couple dozen. I saw no one at Cox–not even volunteers.
…Keep in mind the food tent for Mitt away to the left was FULL at this time, while 1/3 of Hilton was still full of yellow. Mitt may have won really big here…