Gano is the second highest rated kicker in the draft, which could mean he goes as early as the third round. Unlike the other three I listed, Gano also has a advantage in that he was invited to the combine to work out for the scouts, which makes him the front runner of this group to be drafted.
Antone Smith had a very impressive Pro Day running a 4.33 forty. The Patriots were impressed enough to pull him aside later on for a private interview. Even with his pro day I think it's more likely that Smith is brought into an NFL camp as a free agent.
Greg Carr in my opinion is the most likely to be drafted even ahead of Gano. Carr's production dropped off drastically with the arrival of Jimbo Fisher who prefers smaller quick receivers for bubble screens. But at 6'6 Carr is a red zone threat that most NFL offensive coordinators would like to have. ESPN the Magazine's Vincent Verhei has a formula that projects receivers production in the NFL (Note: formula was developed off of production by first and second round picks only). It is TD's per game multiplied by Yards per catch to give you a super score. Of all the available receivers in this year's draft Greg Carr (10.5) ranks third in super score behind Michael Crabtree (21.3) and Jarett Dillard (17.4) of Rice. Carr's score is higher than Jermey Maclin of Missouri and Hakeem Nicks of UNC, and Percy Harvin all of whom are projected to go in the first round.
Tony Carter's stock has been on the rise since pro day. The Patriots came to give him a workout in Jacksonville, and the Houston Texans flew him out for a visit. Carter is very talented and has a great football IQ but his size (5'9) will probably prevent a team from using a draft pick on him. But he will certainly be signed as a free agent and once in camp I think he has a legitimate shot at making an NFL roster.
Michael Ray Garvin's future is more likely in track than football. No team will take him as a corner (unless they have not seen any film of him... ever). Garvin could however find a niche as a kick returner. Garvin was second in the nation last year with a return average of 30.1 yards per return. I think Garvin will be singed and not drafted as well. He should be interesting to watch in the pre-season to see how his speed translates to the NFL returning kicks.