I don’t have any PowerPC machines going any more. But for those who do, it seems that a modern web browser might still be an option: http://www.floodgap.com/software/tenfourfox/
The JIT does work on G3, but unfortunately you won't get much benefit from the accelerated codecs as there's no AltiVec. But, at least the G3 version has compiler tuning.
Just watch out for the creator, he's a bit of a jerk.