Well, since you’re talking about a widget of Links…. why not just use the default Links widget that was part of core up till 3.5?
http://wordpress.org/plugins/link-manager/
If you insist on limiting it to showing the latest 5 links, you’re going to have to write a bit of code (that I’m not convinced is worth it). Possible approaches include:
- Filtering the output of said Link Manager widget
- Creating a custom post type called ‘Sidebar Links’ and then writing your own widget that displays the 5 latest
- Creating a totally custom interface and storage mechanism from scratch (definitely not recommended)
Another options is using something like Options Framework (http://wordpress.org/plugins/options-framework/) to add some Theme Options. You could add Link 1, Link 2, Link 3, Link 4, and Link 5 as options. It’s not an amazing user interface, but it’s another quick way to accomplish basically what you’re looking for.