Portable hidey hole: This is just like a Portable Hole, but a creature may enter the portable hole and seal it up behind them. Every day, the creature must make a Stealth check with a +10 bonus which is used against all Perception checks. A creature in the hole may make Perception checks at a -10 penalty to hear what's going on outside.
While some items may get mechanically better (for instance, a +1 sword becomes a +2 sword), it's more challenging to improve items that don't have numeric bonuses. I thought I'd go through the Wondrous Items in the 4e Player's Handbook and give examples of how each could gain powers that reflect their history.
Inside the hole it is cramped and dark, with enough air for one Small or Medium creature with no fire. It is possible to eat and perform other quiet activities inside the hole. Loud activities will grant perception checks to nearby creatures.
hobbit halfling hole: This portable hole is not a nasty, dirty, wet hole, filled with the ends of worms and an oozy smell, nor yet a dry, bare, sandy hole with nothing in it to sit down on or to eat: it is a halfling hole, and that means comfort.
Notch's Portable Mine Shaft: At the bottom of this Portable Hole is an unusually soft stone surface that, with proper mining tools, can be tunneled through quickly but loudly, in any direction, at a rate of 1 foot/hour. Tunnels and shafts can be excavated up to a maximum distance of 15 feet from the portable hole. If a tunnel breaks through into an area of open air in the real world, the digger can step through into that space. When the portable hole is removed from the surface, all tunnels are removed and the original surface is unharmed.