Add this to your .vimrc:

autocmd FileType python set omnifunc=pythoncomplete#Complete
autocmd FileType javascript set omnifunc=javascriptcomplete#CompleteJS
autocmd FileType html set omnifunc=htmlcomplete#CompleteTags
autocmd FileType css set omnifunc=csscomplete#CompleteCSS
autocmd FileType xml set omnifunc=xmlcomplete#CompleteTags
autocmd FileType php set omnifunc=phpcomplete#CompletePHP
autocmd FileType c set omnifunc=ccomplete#Complete

Try it out:

$ touch index.html
$ vim index.html
type: <ht[CTRL-X][CTRL-O]

You can specify the search path(s) used by ld at runtime to find shared objects by building your program with the -rpath option:

$ gcc -Xlinker -rpath -Xlinker /path/to/my/libraries filename.c

This is the equivalent of:

$ ld -rpath /path/to/my/libraries filename.o

If you want to list the symbols of your object code, you can use the nm command:

$ nm object_file.o