Okay. Spells are split into two categories: "General" recharge, and "Specific" recharge. Your post is running in the mindset of the specific recharges -- depending on the power and cost of a spell, they can take anywhere from 5 minutes to a full day to recharge.
General recharge spells, however, can be used much more frequently -- your highest-level general spell will never take longer than 7 rounds to recharge (5 rounds for spontaneous casters). There's a trick, though: every time you cast a general-recharge spell, you lose access to all of your general-recharge spells of the same level until the one you just cast has recharged. The time this takes is based on a die roll -- currently, our 0th- and 1st-level spells take 1d6+1 rounds to recharge (spontaneous casters instead use 1d4+1). (Note that metamagic versions of general-recharge spells trigger a recharge of their effective spell level -- a
Maximized Fireball would force a recharge of your 6th-level spells, not your 3rd-level spells.
So, for example, when Iota casts
Detect Magic as a 0th-level Druid spell, I roll 1d6+1. Until Iota's Initiative count has come up those 1d6+1 more times, he can't cast
Detect Magic or
Flare, his two general-recharge 0th-level Druid spells.
Light (his third 0th-level Druid spell), however, is on a separate, specific timer. After casting it, Iota has to wait a full hour to cast it again, but he's allowed to cast
Detect Magic and
Flare as much as he desires while waiting for
Light to become available again. (Of course, he still has to wait for the general spells to recharge in between casts, but on average he can still cast one of his general-recharge 0th-level Druid spells twice per minute.)
Because of this, "preparing" spellcasters only need to prepare one copy of each spell they wish to use several times in one day, giving them a slightly wider variety of spells to choose from. Since spontaneous casters are limited to the handful of spells that they have learned (usually lower than the number of spells-per-day that they are normally allowed to have), they instead have shorter general-recharge times. (Note that you can't get around long specific-recharge times by preparing the same spell in multiple slots -- casting one copy would force all of them to recharge, and metamagic versions of specific-recharge spells take several times longer to charge.)
http://www.d20srd.org/srd/variant/ma...hargeMagic.htm has all of the Core/Open Game Content spells in a nice, alphabetized list, along with their recharge times. There's also a table that shows how long your general recharge times are based on your class and the highest level of spell you can cast or prepare.