I've never had a problem with one player's ideas coming from another character's mouth.
Let's say Bob, playing the 21 Int wizard, doesn't have much of a head for figures. Carl, who is playing the 6 Int barbarian, loves mathematical puzzles.
An in-game problem arises where a door must be opened by completing a numerical sequence. Carl sees the answer instantly, but he knows that "Ooh, Throg think answer is 21!" will be out of character. Bob is completely lost.
I see some OOC conference here as helping Bob to portray Zamfar the Magnificent's dizzying intellect, despite Bob's own being less stellar. Carl explains the puzzle and its solution to Bob, and Zamfar acts upon the information.
Similarly, if Bob is playing his first ever wizard, while Carl is a long-time arcane-class player who's trying out the barbarian for some variety, it makes sense to me that Carl might occasionally remind Bob that his Spellcraft skill might give him some hints about what just happened.
It doesn't have to be Throg saying to Zamfar "Hey, you know spell what do this?" It can be Carl suggesting to Bob "There's a 5th level spell that would fit here, but we'd need to go looking - Zamfar would probably know about it."
-Hyp.
