This is about what plugins you find were the most effective and compatible feel free to leave mild notes of tweaking  you had to perform and experiences with said plugin. 

Please do not post about developers here only their plugins.

Personally, I have noticed Chrome to be a giant pain in Oxwall's ass however, some of the plugins I feel to be awesome are:

Video Group Plugin:

This worked right away with the minor tweak of video size, I still have not figured out how to "Center" the videos however, I made the video fit left to right by editing the default embed size for my current theme. (each theme varies in width x height)

Photo Group Plugin:

Another with great potential and well made.

Thu this uses the default photo viewer you can use google+/facebook photo viewer after contacting the support system (Custom tweaking this is not suggested without knowledge).

User IP Tracker:

This plug-in works great for what it says it does "traces users IPs" Though keep in mind that doing things like this could raise fear in your member base so I suggest making sure member understand what it is, why you have it for security and that you don't disclose any personal information that you receive. 

Privacy Policy: "Your personally identifiable information is kept secure. Only authorized employees, agents and contractors (who have agreed to keep information secure and confidential) have access to this information. All emails and newsletters from this website allow you to opt out of further mailings."

Members Flag:

This plug-in works with IP tracker and delivers each members country location so you can remove the question from profiles. In saying this members can hide this flag with privacy settings if they wish to keep it hidden.

Advanced Poker:

This plug-in can be super fun we recently changed the language to say "Actions" to remove the facebook poke feel. Some of the actions we have created became fun inside jokes like insult "user yelled, "you're a minecraft pig!" at user" or Mana "user refilled mayonnaise for user". To avoid spam the plug-in does come with a days till poke expires setting.

Cool CKEditor

This is a good WYSIWYG editor just some features don't work right out of the box in Oxwall. I would suggest if you want better results to enable HTML and use source code to make horizontal lines, bullets etc.

Games

Worth every penny if you like games, These days browser based games have made a big leap with Unity's game engine. This allows full 3-D games with modern textures. Adding and removing games are easy just make sure when setting up a slug don't us symbols or the link won't work. (Keep it plain text)

Group Cover

Another good plug-in to allow your groups to shine. My only issue is the description section in the current version doesn't have it's own box or social buttons. It's kinda this random square just under the cover image. I'm sure this will be worked on for future updates.

Member Awards

This plug-in allows you to create awards/achievements.

This is a good way to have people using all aspects of your site on average people get 1 point per post or update. You might be worried about spam however, I have not had this issue thus far.

Forum Signature

This is a must have for the forum enthusiasts. In the mid-late 90's Signatures was a way to say "this is me". It's pretty straight forward and easy to use. Supports Photos and links.

I have other plug-ins that can be talked about however I'll leave the rest to the community to talk about and feel free to ask questions and leave some of your own "positive" feedback about the plug-ins you like the most. Heck talk about some of the ones I posted about to!