It even counts spells that target multiple creatures and/or objects as an area effect spell.
Form how it's worded it seems like Chain Lightning would count (but not haste).
It just makes you want to roll up a Mystic Ranger / Arcane Archer doesn't it?
Let me help with that then.
Hunter's Mercy (Spell Compendium, p. 117)
Level: Ranger 1,
Casting Time: 1 standard action
Duration: 1 round
Your eyes glow red, but you see the world as normal except when you look at your target. A small glowing dot reveals the creature's weakest point.
This transmutation makes a bow strike true. Your first hit with a bow (not including crossbows) in the next round is automatically a critical hit. If you don't hit in the round following the casting of this spell, the effect is wasted.
It's pretty much always beneficial.
Level 1~5: lose one attack to effectively deal three putting your net gain to +1 over two rounds.
Level 6~10: upgrade to Karoti Resin, -2/+3, net gain of +1 over two rounds.
Level 11~15: -3/+3, no real net change over two rounds but you're guaranteed to trigger in burst-like WSAs.
Level 16+: just use Quicken Spell, as a Mystic Ranger you've had 5th level Slots for six levels now.