How do I bridge or integrate with SMF?
The first step is learning about the integration hooks (http://www.simplemachines.org/community/index.php?topic=173483.0) that SMF has built in. If you have questions to a specific hook, we have a discussion in progress (http://www.simplemachines.org/community/index.php?topic=173505.0) that may have the answer to your question. You can also ask questions in our Portals, Bridges, and Integrations (http://www.simplemachines.org/community/index.php?board=33.0) board.
Where can I find a bridge between SMF and my software?
Feel free to look on our Bridge (http://www.simplemachines.org/download/?bridges) download page for our current officially released bridges.
I can't find a bridge with my software on the download page, what do I do?
If you are unable to locate a bridge for your software, it may be possible that we simply don't know about it, or haven't had a chance to create it yet. You have two options: one is to start digging into the code and create an integration, or you may request a bridge (http://custom.simplemachines.org/bridge_request.php). Before requesting a bridge, please search first to see if there have been any prior discussions for that piece of software. A bridge may not be possible due to licensing restrictions or programmatic reasons.
I've heard so much about SMF and Gallery2, yet I don't see a bridge for it on the download page. Help!?
Never fear, we haven't forgot about you. Take a look at the integration topic (http://www.simplemachines.org/community/index.php?topic=46281.0) by Oldiesmann.
Are there any tools available to make this integration stuff easier?
Sounds like a great idea. Recently, andre nickatina (http://www.simplemachines.org/community/index.php?action=profile;u=112004) has been working on tools to do just that. In case you would like to try his tools, have a look at his New tools to help integrating SMF with something else (http://www.simplemachines.org/community/index.php?topic=453008.msg3164286#msg3164286)
Edit by AngelinaBelle on September 19, 2011: Added link to andre nickatina's tools