I remember being a graduate student, working on a class project for my Wireless Communication course and trying to implement a simple OFDM modulator/demodulator to prove the resiliency to frequency selective fading of such modulation. Sometimes, when one is working on signal processing in Matlab, you need to filter a signal and a quick filter design is necessary.

I just randomly came across a very useful online FIR filter design tool. It allows you to get the filter coefficients in a rapid manner for some given specifications. Not reinventing the wheel, but I just added it to my favorites as it could be very useful some day. You can find it here.