*note this list is not fully complete

ABBC3 replaces phpBB3's BBCode buttons with icons in a beautiful and highly customizable toolbar. ABBC3 also adds many new and useful BBCodes giving users more ways to customize their posts. It also improves some of phpBB3's built-in BBCodes and supports your own custom BBCodes. Additional features include an Image Resizer with various Lightbox styled expanders, and Auto-Embed Video for dozens of media sites and file formats. ABBC3 is a sleek addition to your phpBB bulletin board.
VSE & leviatan21

Allows administrators to select which mod links to display in the overall header and to decide which groups can see them.
Helter Skelter

Adds a new option for ACCOUNT ACTIVATION to the board. Newly registered users first have to validate their email address and then administrators have to activate the account.
Although a new ACP page is added for one click verifying new registered users. On this page you see the all necessary profile details and you can activate or delete the user and do all disallow and banning options if you want.
Martin Truckenbrodt

During user registration, this MOD makes a number of checks to see if it can find errors with the information given by the user. These checks are;
* Checks if the username is available or has already been taken.
* Checks that the two passwords entered are the same (if both have been entered).
* Checks if the first email address is in the correct format. If it is then it does the next check:
* Checks that the two email addresses entered are the same (if both have been entered).
Luke Cousins (LoonyLuke)

Prevents spam on your phpBB3 forum.
EXreaction

Adds a calendar to you forum with the ability to add events and post topic events
livewire Stu

Adds an easy to use FAQ Manager to the ACP.
EXreaction

This mod allows to show first post of topic on top of it's every page in phpBB3.
rxu

Adds a chat page to your forum
RMcGirr83

The original phpBB3 Portal system. Michael O'Toole (Michaelo) phpbbireland.com

Adds a Knowledge Base to your Forum. Tobi Schäfer

Replaces static buttons from styles/*/imageset/en with buttons that use css and language variables
This eliminates the need to port templates to each installed language HelterSkelter

This hack displays, under the online users list, a list of all the registered users who visited during the last XX hours.
It can also display the list of the users who didn't come. Justin (sanis) [url=http]http://stotis.net/[/url]

Adds a photo gallery to your forum.
This is a port of smartors gallery by nickvergessen