lol if you use the search you will find this topic has come up alot.. and for the most part no not really. lol you can see if the yellow extends on the throat and check the size of the eardrum.. but it is difficult unless you have other frogs from the samebatch to compare to. if you look in my frog pictures you can see shots of mine through its stages of growth over the last 4 months and mine is a male.
In general it's very difficult to tell. Often times you have to wait a little bit to gauge the relative growth rate in a batch of froglets, but even then it's hard to tell. Often times sexing is difficult up to about 4 to 5 inches in length, at that time sexual dimorphism will often become more evident, ie - females will retain dorsal stripe, and lose their appetite, etc. Not to mention they grow much slower, for example, nickbachman, a member on this forum, has had a pyxie since last july and she's about 4 inches, whereas Ive had mine for 5 months and he (hopefully) is almost 6.
In short, look for the heftier specimen in a related batch of froglets, if not, only time will tell. My pyxie just recently got very dark and is exhibiting hopeful male characteristics, though his throat isnt all too yellow. We'll see.
Indeed, my pyxie Borchmore's growth rate has slowed a lot. This has led me to believe Borch is a female. She still has a little remnant of a dorsal stripe, though she is quite yellow in the arm/throat region. For judging sex in pyxies, time will tell. That's the main thing.
I am fortunate enough to have 2 comparison frogs from the same batch which is nice.. also I have heard it croak which is a good indicator indeed. a friend of mine has another male and a girl I know has one of the others from the batch and it is only half the size of ours if that.