Wait for the mods mate. It's funny how people forget that Oblivion wasn't any better when it first came out, it had tons of bugs and really didn't have better quests or more content.
True. Oblivion is UNPLAYABLE without mods. Skyrim seems likely to be easier to mod as they have quite a few interesting effects Oblivion never had.
Hold down to continue effect allows for:
1. Control/Dominate NPC like a puppet as long as you are concentrating. Makes more sense and better balance.
2. Spells which start off slowly but builds up damage the longer you maintain it. (As lightning storm should have been)
3. Spells that need long "incantations" but provides extremely powerful effects like instant kill, permanent dominate, baneful polymorph, flesh to stone and so on.
4. Legendary unique summons that are unkillable as long as you are maintaining the spell. Killing someone may even charge them up to be more power the next time.
Multiple permanment traps:
1. Rune Guardians, conjure skeletons to defend a location if triggered
2. Runes with other effects such as paralyze, frenzy, slow
3. Runes that blow people across the room into some other trap!
Using corpse as a resource:
1. Raisen zombies that raise other zombies if they kill the opponent, creating an undead army
2. Summon multiple spiderlings from corpse
3. Corpse explosion, high poison damage for lower cost compared to runes
Those above are all effects already built into the game that could be possible with a little tweaking of existing spells using the construction set.