Walther PP, PPK and various clones. They had their day, but now it's too large to pocket carry and if you are going to carry one on your belt either IWB or OWB, you can carry something of similar size and weight in a larger caliber and higher capacity.
I own two Walther PPs (one in 32ACP and one in 22LR), as well as a CZ-70 and a beautiful East German Makarov. Fun range guns and nice shooters, all. However, they are very low on my CCW and SD list. I'd much rather carry my Colt CCO, Ruger SP101, S&W 642 or CZ40 before one of these.