+Japan
+HK
+Taiwan
+Seoul
If you like you can also hear China to the list, according to Google. I did say that I couldn't think of any others, but naturally that didn't mean that there weren't.
However on the flip side as far as countries that don't use them are concerned:
Finland stop writing checks in 1993, the Netherlands in 2002 and Poland in 2006. Germany, Belgium and Switzerland have also followed suit. Austria, Belarus,Czech republic, Hungary Latvia, Portugal, Romania, Slovakia Slovenia and Ukraine also do not accept cheques. I think it is fear to suggest that the vast majority of European transactions are now electronic.
New Zealand was phasing them out too, mainly because most people no longer use them - not sure if that process is complete yet.
In countries with fragmented banking systems such as the USA they're certainly useful. However they're exceptionally easy to Falicify.
The countries that have done away with them have done so predominantly because of the costs and time associated with processing them. Electronic systems on a whole are far faster, safer, more convenient and more accurate. I'm not saying they're not without their issues, of course they are. Predominantly because they're designed, programmed and operated by us humans!