Bajdi:
May I ask what you are using them for? When I started out with Arduino I bought a whole bunch of 74xxxx IC's. But haven't done much with them.
I started out doing stuff with 7400 ICs just prior to picking up Arduino. I did a bunch of stuff, counters, adders, a multiplier using the 74284/74285, a text scroller using 16 segment displays, EEPROMs, and 7400 logic. I wanted to know some of this basic stuff before working with microcontrollers. Without any microcontroller in the design, these circuits are very useful to get data on a display.