There are front-end editing snippets, PubKit comes to mind. Depending on what exactly needs to be managed by these users, lists such as FAQ question/answer pairs, you can set up Jot to handle.
On the other hand, it’s not at all difficult to configure a manager user (or several of them) and the QuickManager plugin to control and limit where a manager user can go and what he can do. A manager user can be blocked from accessing the Manager at all, going to a given page on login, and the QM can be given custom buttons and set up to edit various parts of a page. That’s the route I prefer to go. You can even create a front-end "Manager" page with links to various pages that most commonly need editing, or if you have a MaxiGallery management page or anything else with editing or management tools. And there’s a snippet that will log in a Manager user from the front-end, so he doesn’t have to browse to the Manager login page. The major advantage to this method is that admin pages can be unpublished, and the manager user can still see and edit them, while your regular web visitors can’t get at them.
I usually put an "admin" link unobtrusively in the footer somewhere to not get regular visitors distracted.
When editing a resource (in the Manager or QuickEdit), to create a link put the text you want to be the link, then highlight it. The little link icon will be enabled in the editor’s tool bar; click on it to open the insert link dialog. The second field will be "Link List", with a select drop-down to choose the resource you want to link to. Click on the one you want, ant the proper MODx tag will automatically be inserted for you.