There is one thing I really like about D&D 4th edition is the ritual system. I think it gives an excellent way of raising the magic level of a D&D campaign without ditching the vancian system. The basic innovation is that you spend gold in the form of components and you can cast a spell without memorizing it. Problem spells can be handled by require specific components that are rare and expensive.
Any spell in the rule books can be casted as ritual. The casting time is 10 minutes. The component cost is the spell level SQUARED times ten gp. (level^2 * 10 gp). Components can be bought at most magic shops like the Sorcerer’s Supply Shop in the City-State of the Invincible Overlord. As an option the referee may wish to impose specific component requirement on certain spells particularly for those 7th level or higher.
The intent of this system is that most utility spells are cast via ritual in the Majestic Wilderlands. This changes the role of scrolls. For Magic-Users and Thothian Mages, they are mainly created to increase the number of combat spells that can be cast. They are of particular importance to Orders who do not memorize spells.
I just realized that using this house rule provides a nice explanation of the differences between Chainmail Magic and D&D Magic. In Chainmail turns are a lot longer than rounds allowing the Chainmail Wizards to cast spells via rituals. As long as the supply of components don't run out he can cast even if the battle lasts all day.