Putty is ok if the data is actual ASCII. For actual binary data I've used realterm (it is quite confusing in my opinion, hard to understand what it is doing) but I don't really like it. I should probably check out some of the solutions mentioned in this topic.
Having dealt with some serial data in some of my own software using Qt and QSerialPort I've seriously contemplated on making my own serial terminal software for binary data, having not found any good solutions...