contrib/hstore will save you.
See http://www.sai.msu.su/~megera/postgres/gist/hstore/README.hstore
for details.
thanks. i didn't know about it, and it looks great. but i'm not sure if we will be able to use it - my developers use java + hibernate, and they say it cannot work with any "fancy" datatypes (including such a base things like "INTERVAL").
i will definitelly use is though in my other (not hibernate-dependant) projects.
best regards
depesz