Uzbl

Right.
My guess is this is because we do not handle compressed pages.
see:
dieter@dieter-ws-a7n8x-arch ~ curl -I http://en.wiktionary.org/wiki/inquisitive
HTTP/1.0 200 OK
Date: Thu, 25 Jun 2009 00:49:48 GMT
Server: Apache
X-Powered-By: PHP/5.2.4-2ubuntu5wm1
Cache-Control: private, s-maxage=0, max-age=0, must-revalidate
Content-Language: en
Vary: Accept-Encoding,Cookie
X-Vary-Options: Accept-Encoding;list-contains=gzip,Cookie;string-contains=enwiktionaryToken;string-contains=enwiktionaryLoggedOut;string-contains=enwiktionary_session;string-contains=centralauth_Token;string-contains=centralauth_Session;string-contains=centralauth_LoggedOut
Last-Modified: Mon, 18 May 2009 14:25:55 GMT
Content-Encoding: gzip
Content-Length: 5496
Content-Type: text/html; charset=utf-8
X-Cache: MISS from sq38.wikimedia.org
X-Cache-Lookup: MISS from sq38.wikimedia.org:3128
Age: 60805
X-Cache: HIT from knsq2.knams.wikimedia.org
X-Cache-Lookup: HIT from knsq2.knams.wikimedia.org:3128
X-Cache: MISS from knsq30.knams.wikimedia.org
X-Cache-Lookup: MISS from knsq30.knams.wikimedia.org:80
Via: 1.1 sq38.wikimedia.org:3128 (squid/2.7.STABLE6), 1.0 knsq2.knams.wikimedia.org:3128 (squid/2.7.STABLE6), 1.0 knsq30.knams.wikimedia.org:80 (squid/2.7.STABLE6)
Connection: close

It uses gzip compression

It's definitely a problem with Content-Encoding, when I hardcode "Accept-Encoding: gzip" I see the same symptoms.

WebKit sends Accept-Encoding: identity, so servers shouldn't be gzipping their responses. A WebCore/ChangeLog says:

2009-05-28

Simplify the Accept-Encoding header we are sending out, for it
seems some servers do not enjoy parsing the full, explicit
version.

So maybe WebKit newer than 1.1.8 will fix your problem?

For a better fix (because gzip is nice), there's a libsoup bug about supporting Content-Encoding: http://bugzilla.gnome.org/show_bug.cgi?id=522772

No that new webkit won't fix the problem because some web masters just assume all web browsers accept gzip and send it to everything without reading the Content-Encoding header. Another example: http://circuitdesignonline.com/

Ugh, circuitdesignonline assumes that you can do gzip AND that you can do application/xhtml+xml. Even if you explicitly state otherwise. That's pretty terrible.

Hm, 'inquisitive' page opens fine for me... (I'm using uzbl 9a32a5f8c8d18d143cf8b4a89531c866679026c7, libsoup 2.26.2, webkit 1.1.10)
And circuitdesignonline.com says:
___
This page contains the following errors:
error on line 1 at column 1: Encoding error
Below is a rendering of the page up to the first error.
---
(but with nothing below)

According to https://bugzilla.gnome.org/show_bug.cgi?id=522772 the gzip support was included in libsoup-2.28.2. How do i utilize it?

Loading the largest page on wikipedia works fine for me http://en.wikipedia.org/wiki/Line_of_succession_to_the_British_throne using the latest webkit version.