If you want to merge branches in your projects using a Mac OS X, you'll probably miss how straightforward is to do that with the TortoiseSVN client.
Mac has many SVN-fashioned clients where you can fall in love when you see the GUI, but when it comes to do a merge it seems that all they have forgotten to include support for it. I haven't seen any free or comercial application for Mac that integrates all the subversion commands in the same tool without pain. You need always a couple of tools and sometimes use the terminal commands (I do this the most in Mac).
Returning to the specific svn command merge, here are the only tools that you can use to accomplish that task:
Graphical subversion client with diff and merge tool. http://subcommander.tigris.org/
Multiplatform utility for merging and comparing: http://www.sourcegear.com/diffmerge/ (not SVN specific)
Guiffy is a normal diff/merge application, you don't need to use Subversion, but it comes with support for CVS/SVN. http://www.guiffy.com/
And that's all. I've spent many hours looking for more apps, but I haven't found any helping me with the merge integrated with SVN. If you find anything let me know and I'll add it to the list.
UPDATE (Added SmartSVN)
SmartSVN is the most complete solution for Mac I've seen. It runs on Windows and Linux as well. Although it is not a Cocoa application and doesn't accept things like drag and drop it does everything you might need, and speaking about merge:
- Merge from 2 sources
- Reintegrate branches
The application allows to create several projects, browse them (very clean and neat), see the logs inside the context, see diffs, resolve conflicts, tags, branches, logs, filters... everything!!!
I don't understand how this application isn't more popular, since is the missing app for advanced mac developers and works on any platform.
If you find anything interesting please let me know and I'll add it in the list.