hmm... suggestions... for bands with similar sounds, i dont honestly listen to too many, most others really don't catch my attention the way katatonia does... for similar "feel" though,
- definitely check out anathema - my personal favorite albums are alternative 4 and judgement, altho their new one ' a fine day to exit' is also wonderful (some certain people on this board will disagree with that... me, i like it)...
- amorphis is another good band with a similar sort of attitude, if a little bit more 'rock.' top albums, imho: elegy and tuonela...
- jeff buckley is very different than katatonia musically, but occupies a very similar emotional area, and is fantastic singer/songwriter-esque stuff...
- and many, many more...
what is it you find most appealing about katatonia? (if that's an answerable question)... knowing that, can probably suggest more things that you might like... hope this helps!!