Magical Creatures as a source of Magic Items

One line in the 3.0 DMG in the cursed magical items section mentions how magical creatures can influence (i.e. warp) the powers of magic items. If that is possible, why not allow powerful magical creatures to imbue some of their supernatural energies into non-magical items as well? Of course not all objects will gain power and the results may not be what looters will want. Here are some suggestions for various monster types:

First though, items likely to gain magic powers without many (or powerful) side effects are masterwork or better. Those of lesser quality will either remain mundane or gain d4+1 (or more) side effects in the form of curses.

Dragons are the obvious place to start as most species collect treasure and are in contact with it much of their lives. The hoards of older dragons should have many magical items created by the beasts' nature and those items that were magical when the dragon collected or created them (via item creation feats) will either gain side effects or even have their abilities warped to something completely different. The nice sword which was a frost brand might very well be, in effect, a scarab of protection or a helm telepathy.

Aberrations are by their vary nature unnatural and some are very powerful, magical creatures. Some beholders enjoy collecting treasure and could imbue items purposefully with their non-destructive eye rays, though the results may or may not be random when applied to items that are already enchanted.

Magical beasts, even those without a given magical ability, such as hydras, might be able to cause magic items to come into being. Sphinxes are intelligent enough to study this effect and possibly control the results, or at least minimize the side effects.

Outsiders are all over the place for this. Some planes may not allow magic to "leak" and in others, it may be the only form of magic item creation. Angels and devils might be able to turn any weapon or armor they touch to holy/unholy items. Chaos beasts are obviously dangerous to living creatures, but oddly, there is no mention of their effects on objects. A survivor may be fine, but her equipment could be turned into a minefield of powerful cursed items. The same applies to victims of demonic possession and contact with slaadi. Powerful chaos is bad news for everything, including magic.

Humanoids, monstrous humanoid and giants, in the form of spellcasters, may be able to do this, but for most people, it takes too much time and the results are way to wonky. Still, powerful sorcerers may find the coins they carry gain minor (0 level or less) powers because of their blood and all the magic items they wear. Some might even see it as a distraction or hazard of spellcasting. Those races that have longer lifespans (elves, giants, etc.) might find this problem worse as they get older.