I use nedit (http://nedit.org) and here what it provides :
Name : nedit
Perl exclusive :no
Free :yes (GPL)
Perl engine :any
Syntax checking :yes (thru macros)
Syntax coloring :yes
Auto indent :yes
Incremental search :yes
Bracket matching :yes
Folding :no...
Debugger :thru macros
Stepping :thru macros
Breakpoints :thru macros
Watches :thru macros
Bookmarks :thru macros
Suggest & complete :thru macros
Identify errors : no
Interactive Shell :sort of...
Code Snippets what's this ?
Var tree :no
Var evalution :thru macros
Stack module :no
Code browser :thru MENhir add-on
Project : thru macros
Control version :thru macros
Multi document : yes
Split View :yes
IME :what's this?
Docs & Help viewer :thru macros
Module installer :no
WEB : no
FTP :thru neftp addon
HTML export :thru macros
Linux :yes
Mac OS X :yes (with X11)
Solaris :yes
Windows :yes (with cygwin)
And of course it works with most languages out there.