you can make a lot of stuff using opamps. you need to be more specific what is it that you want.
a simple thing you can do is a an instrumentation amplifier using three opamps.
am already woprking on it
but i need a stand-alone circuit....
something like an alarm
how about a temperature controller, using window comparator?
any ideas about that?
try a two window comparator (4 op amps) electronic key i did ths for my school exam but have lost the diagram it is simple anyhow just use some imagination