Not really. Obviously visually. I have had fermentations that looked like the stuff was boiling. I've had some where there was a ton of foam, some none at all. I have had some go from 1.090 to 1.00 in 4 days, some that have taken 2 weeks. Some wines look like nothing is happening but the hydrometer can show you that indeed it is fermenting.
A hydrometer really is the only way to tell whats going on, especially when it comes time to add the sorbate and allow it to rest before bottling.
Most of the gang recommends to look for a constant SG for a few days after sorbate to make sure fermentation has stopped. No way to do this without a hydrometer.
There is a whole discussion on ensuring a good fermentation, but that is a different thread and and has its own set of thoughts.
But, no. A hydrometer is probably the most important tool for measuring and determining activity during a fermentation. As you may have seen, those who come into the forum asking questions and announce they don't have one get picked on good.