Before I run down this list, I should note that the Steelers have one or two valuable free agents, so there is a not-insignificant chance that the Steelers will trade up (as pointed out by betelgeuse in this comment).
With that in mind, here is my collected run down of our projected 1st round pick, from all of the supposed draft-masters on the internet (that don't charge money to see their picks).
The Big Sites
Yahoo Sports - William Beatty, OT, Connecticut
Sporting News - Duke Robinson (G)
Sports Illustrated - Duke Robinson (G)
ESPN's Todd McShay - Tyson Jackson, DE, LSU
Fox Sports - Max Unger, C/OT, Oregon
NBC Sports - DT Peria Jerry, Mississippi
MockingTheDraft - Eben Britton, OT, Arizona
Random Sites Found Via Google
Scout.com - Duke Robinson, OG Oklahoma
draftcountdown.com - MAX UNGER, C, OREGON
newnfldraft.com - Alex Mack, C, Cal
walterfootball.com - Tyson Jackson, DE, LSU
draftking.com - Duke Robinson, OG, Oklahoma
nfldraftdog.com - OT, Eben Britton, Arizona (JR)
thefootballexpert.com - Alex Mack, C, California
A lot of people on this list like Duke Robinson, Tyson Jackson or Max Unger.
It's interesting that everyone on this list has us taking a position on the offensive line, or else Tyson Jackson at DE. That's interesting because Colbert almost NEVER reaches for players in the draft. He is more apt to take the best player available, then to reach for a lower ranked player in a spot we need to fill.
Obviously we need players for the offensive line. The question is this: is the situation dire enough that Colbert will break tradition and reach for an offensive lineman? Or will he just take the best player available?
I'm not a draft analyst, so I have no idea.
In the comments, link me to the drafts that I missed so that I can add them to this list.