I've been thinking, particularly, about how one would Saga-ize D&D. In some ways, it's remarkably easy. Weapons, armor, and the base classes, I finished quickly. And you've seen chunks of my monster conversion thoughts in this space. But what's given me the most trouble, conceptually as well as mechanically, has been spellcasting.
Saga Edition is built around a philosophy of slim books and limited abilities. Even high level Jedi Masters only have a handful of powers to pull out during a big encounter.
D&D, on the other hand, is built around a philosophy of spellcasters with a list of spells an arm long. Show me a 10th level D&D cleric, and I'll show you an 18-page character sheet, most of which is spellbook.
It's reconciling these two philosophies that's causing me difficulty. On the one hand, it's not really D&D without Bigby's redundant finger and cure nasty splinter — on the other hand, do I really want to comb through 500+ spells in the SRD alone and decide who lives and who dies? Granted, there's no reason that cure minor wounds, cure light wounds, cure moderate wounds, cure serious wounds, and cure critical wounds can't easily be compressed into a single spell (not to mention summon monster I, II, III, IV, V, VI, VII, VIII and IX combined with summon nature's ally I, II, III etc.). But even if I do all that, there's still a boatload of spells, and that leaves the problem of figuring out how characters can learn and cast them in a way that's recognizably D&D. 
What SWSE does is there are a total of something like 20 Force Powers, and Force-using characters spend a feat to learn a handful of them, putting them into their "Force Suite." These are the powers that the player can call on during an encounter, and if the player wants to call on a particular power more than once, they have to either put that power into their Suite more than once, or spend a Force point during the encounter to recover a spent power.
That, to me, sounds like a D&D bard or sorcerer — call it "Spell Suite" instead of "Force Suite" and you're good to go. Perhaps wizards and clerics, instead of having pre-set spells, can choose how to fill their "Spell Suite" at the beginning of the day from either a preset list (for clerics) or their spellbook (for wizards). For that matter, perhaps wizards can swap spells in and out of their suite between encounters if they so choose?
The real problem, then, is figuring out how to whittle those 500+ D&D spells into a more reasonable list. They're not all as obviously redundant as cure X wounds; two very iconic spells, fireball and lightning bolt both do elemental damage in an area (a radius and a line respectively), but they're two different types of damage and two different shapes. You can create a single spell, say elemental burst, and let the player choose whether it's a ball of fire or a line of lightning, but that quickly loses the classic flavor , not to mention being a pain in the tuckus to go through and figure it all out.
Anyway, I'm open to suggestions on the subject. I was thinking I might pull out my old, old blue cover D&D boxed set and simply pull the spells out of there — it's hard to get more classic than that — and then only add any contemporary spells that are conspicuously missing from the list. Then if somebody really wants one like, say, repel metal or stone (which I have never once seen cast in any game), it can be converted on an as-needed basis.
 "Why are you trying to do a crazy thing like that to begin with?" You may be asking. That's for another post some other time. For the time being, call it a mental workout.
 "I wanna cast magic missile!" "Sorry, that's been replaced with arcane damage, multi-bolt option." "Gee, how very evocative." "Shut up and attack the large monstrous humanoid 4's already!"