I like ActiveState Komodo on Linux. From what it sounds like, it’s what you want – except for C++ support, which it doesn’t have (unless they’ve added that in the past year), so you’d have to find that separately I guess.
ActiveState’s description of it: “Code client-side and browser-side apps simply and naturally with advanced support for Perl, PHP, Python, Ruby, Tcl, HTML, CSS, JavaScript, XML, and more.”
I also like NetBeans a lot; I’ve only used it for Java (Swing & J2ME/MIDP development (separate projects)), but I liked it better than Eclipse for that, and these days it’s got support for all kinds of different languages/platforms, including C/C++.