I am new to developing Chrome extensions and I used Stack Overflow to ask many questions and got great answers. I finally finished a beta version and uploaded it to Chrome store only for test users. Now I am not sure where to find test users so I decided to ask here. Is there a separate forum where people post their apps or extensions for review?
Where you find testers is a case by case kind of issue.
If your extension solves a very specific problem then I would recommend finding the group that would be the most excited about your solution. Offering limited invites to that group. The group will give good feedback from their desire to get a fully working product.
A different solution is to pay for people to test your application using a service like Amazon Mechanical Turk. This would allow you to incentives your workers and get results fast.
The last obvious solution would be to just release the software as beta to the public and get feedback from them. This is very common for home grown software as it gives you the opportunity for many people to look at the extension.