There are a number of ways links can be made more accessible to those people with disabilities.

Tabbing

Users who do not or cannot use pointing devices can tab through links and, as such, links should be in a logical tabbing order. The tabindex attribute allows you to define this order although if the HTML is linear, as it should be, a logical tabbing order should automatically fall into place.

<ul>
    <li><a href="/here.html" tabindex="1">Here</a></li>
    <li><a href="/there.html" tabindex="3">There</a></li>
    <li><a href="/limbo.html" tabindex="2">Limbo</a></li>
</ul>

In this example (which is used purely as a demonstration - it would be quite dumb, practically speaking), tabbing would jump from "Here" to "Limbo" to "There".

The good bit of link-accessibility advice is to write good link text. Have the words the a tags wrap around explain where the link will take the user. If someone is using a screen reader, having the links read out to them as they tab between them, the user will then know what they’re letting themselves in for if they select a link. "Click here" or random words aren't especially helpful.

Link titles

If you have a link that isn't self-descriptive, or the link destination could benefit from being explained in more detail, you can add information to a link using the title attribute.

<p>I'm really bad at writing link text. <a href="/inept.html" title="Why I'm rubbish at writing link text: An explanation and an apology.">Click here</a> to find out more.</p>

Another tip: Don't have links open something in a new window or tab. It's precious to think your page is important enough to stay alive while a user visits elsewhere anyway. We all know how to use the back button. We know how to close windows and tabs, too, but if you can't actually see that that's what has happened, then you are not aware that a new window or tab is open. If you insist on doing this, at least mention it in a link title.

Accesskeys

Access keys allow easier navigation by assigning a keyboard shortcut to a link (which will usually gain focus when the user presses “Alt” or “Ctrl” + the access key).

<a href="/somepage.html" accesskey="s">Some page</a>

For users who do not use pointing devices, this can be a quick way to navigate. The trouble is that there the user may not know what they are unless they are explicitly stated, although some assistive software will tell the user what these are.

Skipping HTML

To aid tabbing, you can supply links that allow users to jump over chunks of your web page. You might want to allow someone to jump over a plethora of navigation links, for example, so they can just read a page’s main content rather than cycle through all of the links:

<header>
    <h1>The Heading</h1>
    <a href="#content">Skip to content</a>
</header> 

<nav>
    <!--loads of navigation stuff -->
</nav>

<section id="content">
    <!--lovely content -->
</section>