Hello, as the title says: what's your IDE of choice to program C++ or Mono under Ubuntu? Is Eclipse a viable way? Is MonoDevelop mature enough? How about other IDEs?
I don't know about Mono, but for C++ I can recommend Code::Blocks. It's not in the Ubuntu repositories though, so you'll have to get the package yourself, but they have precompiled packages for Ubuntu.
KDevelop is quite complete for purely C/C++ development.
For C#, I'd just go for MonoDevelop, as there is no other alternative which supports code-completion. SharpDevelop would be nice to try under Wine.
I find eclipse for C++ under ubuntu to be rather easy to break. It has a lot of hidden stuff that can go wrong (like suddenly refusing to build some project) and the C++ indexer can drive you mad.
I am using NetBeans IDE for C++ Programming. It have a lot of features: C++ Project Support, syntactic and semantic highlighting and more. See this page.
As far as C# goes, you don't really have much, choice, MonoDevelop is the way to go and in my little experience with it, it's good enough (most of my C# work was done in VS2005).
As for C++, I have had success at using Netbeans (6.5 + 6.7beta) for editing and building an old legacy app, which uses handmade Makefiles and lots of other scary things you wouldn't find in any recent C++ project. In our case there was a bit of hand holding to do when setting things up (create the project, then had manually add include paths and what not), but after that, worked almost flawlessly. Code completion worked great, even through various levels of arcane template usage, although it did have trouble in one case (some automatically generated code from Liquid XML 4).
If you are also going to be developing in Java and are not tied to Eclipse or whatever else, I think Netbeans is a pretty good all-round IDE, considering they have support for groovy, php, ruby, and python, if that tickles your fancy.
I'm using Eclipse for Java, C/C++ and PHP, too. I installed Code::Blocks but I don't like its interface, and Code::Blocks can't generate a makefile ( it has a plugin called cbmakefile, but getting it to work is quite difficult ). NetBeans is a really good IDE, but it's a bit heavy, and I can find anything I want in NetBeans at Eclispe.
For Mono, I think MonoDevelop is good enough
Of course, as has been suggested, you can use MonoDevelop for C#. You can also use it for C++ if you so desire. I don't believe it supports C++/CLR yet (or even if Mono supports C++/CLR).
For C++, I tend to prefer simple emacs though. C++ is a rather difficult language to provide some of the more "advanced" IDE features anyway.
For C++ I use QtCreator, version 1.1 has fixed many things. It is simple and powerful.
NetBeans 6.5 with C/C++ plugin. SharpDevelop for Mono.
Both of these are easy to install through the package management tool that comes with Ubuntu.