I completely agree. The Celtics addressed nearly every need they had this offseason. They got a versatile big man (Rasheed Wallace) who can fill in at both power forward and center, they are about to add a nice wing player (Daniels) who should be able to give Paul Pierce and Ray Allen a few extra minutes of rest per game, and they solidified their bench with Shelden Williams and the returning Davis.
An extra point guard is a luxury, but one a championship-contending team such as the Celtics should try to get. Tyronn Lue is at the top of my list. Lue had a tough year playing with Milwaukee and Orlando last season. But the 32-year-old Lue is well liked by his teammates and comfortable in a backup role. Bobby Jackson and Blake Ahearn are two other guys I would look into before training camp.
And no, Stephon Marbury is not an option.
That plan works for me. Ty Lue won't knock anyone's socks off, but at least he's a point guard with NBA experience. He'd be a nice, cheap, backup option that you could plug into the lineup if Rondo goes down for a week or so with an ankle sprain. Jackson is another name that's been tossed around on this site quite a bit. I'll have to look up Ahearn though.