Since I've been criticised for going on for too long with an idea, I'll put a short version at the front, and then elaborate in the long version after that.

The idea: Add some new items that have a new effect, one that shouldn't require a lot of coding (just modifying the teleportation-handling code). The effect? Prevention of teleportation. The primary use for players would be to prevent teleportitis from affecting actions (like eating or reading), but it would also prevent on-demand teleportation. Some such items may even be autocursing or locking, thereby being a danger for any character that might want to use teleportation to escape a dangerous situation.

Elaboration: The main thing I wanted to do here was to provide some sample ideas (already posted elsewhere, but copied here).

1. Astral Shackles - they autocurse and they block all forms of teleportation. These are the basic item, doing nothing more than affecting the ability to teleport. I'm actually tempted to suggest that, to make them a little more risky, they should be autolocking rather than autocursing - so you have to destroy or transmute them to get them off. Autolocking would go very well with the idea of them being shackles. There could perhaps be a way for those with pick locks to be able to unlock them, though.

2. Gloves of Impotency - this is the Wizard's big danger. Autocursing, these not only block teleportation (with perhaps the exception of teleportation traps), but also all spellcasting. They do have an upside, though... I'm just undecided between four options (or a combination of them):

Option 1: Gloves grant resistances to all four elements, death ray resistance, and petrification resistance.
Option 2: Gloves significantly reduce damage due to magic in a direct sense. A magic equivalent of Gloves of Peace, in effect.
Option 3: Gloves help to make melee easier, by boosting accuracy and/or damage (or perhaps by increasing a stat?). This helps to compensate for removing Spellcasting for Wizards by giving them a little more chance in melee.
Option 4: Gloves prevent all stat drains by monsters.

3. Shoes of Anchoring - Definitely the most troublesome of the items, these are autocursing shoes that increase movement costs (equivalent to the effect of cursed SLBs, but unaffected by BUC status), increase water damage based on BUC status, and reduce the weight limit for ice bridges to (BUC) 1750/1500/1000 stones. This can make rivers pretty much a no-go unless you have water breathing, and the movement cost is difficult. The one real upside is that kicking damage is significantly increased. Could be quite useful in conjunction with a circular kick, I suppose. They could also be useful as a thrown item (like throwing an actual anchor).

4. Helm of Astral Stability - This is probably the nicest of the items (but also the rarest), granting real advantages and not autocursing or locking. Not only does it prevent teleportation, but it also reduces corruption (say, by 10 percent, because the astral plane is corrupted, but the helmet prevents any incidental contact with that plane), increases PV, and resists death rays (reasoning: as I see it, death rays don't cause physical death, they're effectively cutting the target's mind - astral form - from their body. This helm blocks that astral knife, protecting you).

I recognise that ideas 2 and 3 would require additional code creation, as they both have additional effects that aren't already in the game... but they just go so naturally with the idea, I didn't want to leave them out. Ideas 1 and 4 are more straight-forward, only requiring code creation for the teleportation prevention effect, and otherwise having effects that should already be in the game (thus pretty much requiring either flags attached to the item or copy/pasting of code fragments from other items). Option 4 could even become a new artifact, and perhaps also provide a stat boost... say, to Mana, or to Willpower.