That's just too broad to be a question. It's also puzzling how you define better or more interesting software.
Most software does only one thing, and does that well.
Sites like freshmeat.net, sopurceforge.net, github.org, gitorious.org, even freedesktop.org all carry interesting projects that you can dip into Try kde for eye candy. You may just want your old software with a fresh skin, theme, or icons. Nobody really knows what you want.