Recently I found out I'd accidentally blocked someone on GChat, and now I'd like to know who else I might have blocked?
How do I figure this out? (I have too many contacts to go through them one by one.)
In gmail chat, as I'm sure you know, you can block or unblock anyone by typing their names into the chat box, hovering over and selecting or deselecting Block PersonX. However, this requires that you know who it is you're trying to unblock.
The best solution I've found for viewing a list of who you have blocked is this workaround wherein you install and run Google Talk using your gmail address. From there you can go to Settings >> Blocked. The "Blocked" section will show you a list of everyone you have blocked and you can block or unblock them individually or in bulk. This should sync back with your Gmail chat, but if not you will at lease know which contacts you want to unblock and can do so using the first method I described (also described here in the Google product forum.)