The pipe dream pick in the first round for me would be Michael Oher, star of the excellent Michael Lewis book, The Blind Side: Evolution of a Game. The book examines the development of football players from high school through the college recruiting process, and also tells Oher's extraordinary life story--he was essentially homeless and illiterate until he was taken in by a family during his high school years.
In the football world, even at the college level, the 6'5", 315-pound Oher is seen as a freak of nature, not only outsized but perfectly, almost preternaturally built to be an offensive lineman, with long arms and a low center of gravity in solidly built hips.
Most mock drafts project Oher will go to the Washington Redskins. Most mock drafts also project that the Patriots will use their first round pick to select a linebacker.
As with most positions on offense, this year, offensive tackle is a position to rebuild for the future, if at all, and to be frank, the Patriots would probably select a player with a reputation for being a bit more, er, cerebral than Oher.
Even the Patriots.com mock draft doesn't show the Patriots using any of their picks to add to the offensive line. I also highly doubt they'd spend any more in free agency on a new left tackle with Matt Light still serviceable and familiar with that position.
However, one mock draft I came across shows the Patriots picking Oregon Duck offensive lineman Max Unger. It appears Unger has spent most of his time in college playing center, but he'll occasionally move out to left tackle. Like many college players, Unger will probably move positions in the pros due to his size--6'5", 285.
I'm also intrigued by the potential of a former center, or possible substitute center, playing left tackle. Offensive line is a cerebral position, and center is the most demanding. A college player who could handle the center role would be a great addition to a Belichick offense at tackle.