Here are a few UnrealIRCd modules written by me. For other free modules, try google or the official module page at www.unrealircd.com -> modules.
Note that I also have much more advanced paid modules, and offer custom coded new modules, see the Products section.

*NIX Module pack: All the modules below are now also available in 1 package (just 9kb), which also contains an easy-to-use installer with dialogs etc. Use of this ModPack is especially recommended if you are installing multiple modules. You can grab the latest modpack here.

Windows users can download the win32 module pack which contains all my modules and comes with a full installer.

1.1 [2010-03-01] (will be in Unreal3.2.9+)
This module protects against the Firefox XPS IRC Attack (and variants thereof).

CHANGES:
v0.1, 2009-09-12: Proof of concept
v1.0, 2010-02-28: Public release
v1.1, 2010-03-01: Fixed set::nopost configuration not working

0.2 [2004-10-05]
This module is against the MyDoom trojan/virus, use it if you get spambots that do like:
'Shakira Dancing virual girl , visit my private server while im online... http://1.2.3.4:1234/'
It detects these bots before they are even fully connected.
NOTE: If you don't have such bots there's no need to install this module, it 'only' affects 40 IRC networks.

CHANGES:
v0.1, 2004-09-21: First release, confirmed to work on at least 1 network.
v0.2, 2004-10-05: Forgot to include 4 names, did so now.

1.3 [2011-11-12]
This module tries to detect random users (bots) and kills them (or optionally: *line them). Note that by design this module could kill innocent users (that look like having random nick/ident/realname) and might also miss some "random" bots (because for the module they didn't look random enough), that said.. the module seems to do a good job :).
CHANGES:
v0.1.1, 2005-01-06: Public release
v1.0, 2005-06-21: Stable release, moved nearly all configurable parts to config, 10x speed up, and more..
v1.1, 2005-07-21: Fixed an issue with digits and some other checks, this resulted in a too low score.
v1.2, 2005-12-09: Added 'warn' action (warning only), added logging to ircd.log (if enabled).
v1.3, 2011-11-09: Convert nick/ident/host to lowercase before doing random checks (convert-to-lowercase)

0.0.2 [2003-10-21]
This module will protect your users against the mIRC 6.0-6.11 and 6.12 exploits by blocking suspicious dcc requests.
CHANGES:
0.0.1: First release
0.0.2: Added detection&blocking for 6.12 exploit

2.1 [2010-10-26]
This module adds an extended ban ~T:<action>:<globmask> by which you can instruct the ircd to take action upon encoutnering certain words in the channel ("text ban"). Supported actions are 'block' (block the entire sentence) and 'censor' (replace the word with <censored>). See the README for more information.
Example usage: +bb ~T:block:*http://* ~T:censor:*badword*

CHANGES:
0.1, 2005-06-24: First release
1.0, 2005-09-10: Now no longer experimental, no code changes
2.0, 2007-01-22: Added a 'censor' feature, which will replace matching words with <censored>
2.1, 2010-10-26: Fixed compile problem if you disabled the censor feature

1.0 [2006-08-08]
This module will strip control codes (bold/underline/reverse) if the channel is +S, and block such messages if the channel is +c.
CHANGES:
0.1: First release
1.1: Performance improvements, fixed 'cannot send to channel' message causing it not to be displayed in the channel window on most clients.

0.0.6 [2004-03-07]
This module adds a +D usermode that acts just like +d (don't receive channel msgs) but for private messages instead, it only allows private msgs/notices from servers, u-lines (services) and opers.
CHANGES:
0.0.2: made it so servers and services override +D
0.0.3: installer/README fixes, nothing changed in module itself
0.0.4: again an install fix: ./build now runs fine at FreeBSD.
0.0.5: fixed bug where module would stop working on /rehash!
0.0.6: "big" code cleanup, fixed bug where usermode +D would be lost on /rehash. Also made the module send a notice to the sender if the msg was rejected.

0.0.2 [2003-05-02]
This module makes it possible to have a single BOPM scan all clients at all servers.
It's simple: this module should be loaded at ALL[*] servers. Then, if someone connects
it will forward the connection notice to the nick specified in set::bopm-nick.
Note that the module will check if the person specified by bopm-nick is an oper,
if not it will not send a notice (just to be sure simple users can't fake BOPM
if the remote server is down).
[*]: All, INCLUDING the one the BOPM client is connected to and including hubs (even if you don't have users at it)
CHANGES:
0.0.1: First release
0.0.2: install fix: ./build now runs fine at FreeBSD.

0.2 [2004-02-27]
This is a simple module that will turn all NOTICEs from services (U-lines) into PRIVMSGs.
It's really a matter of taste if you like this or not, I just offer it here for the people that use services where this option is not available (eg: ircservices).
CHANGES:
0.0.2: Public release

0.3 [2004-12-29]
This module adds the ability to 'redirect' users to another server. Note however, that this is only supported by a few clients (mIRC).
It adds a /JUMPSERVER command:
/JUMPSERVER <server>[:port] <NEW|ALL> <reason>
or:
/JUMPSERVER <server>[:port]/<sslserver>[:sslport] <NEW|ALL> <reason>
If 'NEW' is chosen then only new (incoming) clients will be redirected/rejected.
If 'ALL' is chosen then ALL clients (except opers) are redirected immediately (+incomming).

CHANGES:
0.0.1: Public release
0.0.2: Added option so you can redirect SSL users to another server
0.3: Fixed display bug (said enabled when it was not enabled at all)

3.0 [2004-12-11] (no longer needed, implemented in Unreal3.2.3+)
This module adds a chanmode +j which can be used for join flood protection.
Basically it throttles joins per-user to x:y.
Mode syntax: /mode #chan +j <joins>:<seconds>

CHANGES:
2004-12-11, v3.0: Now maintaining this module (originally coded by AngryWolf)

3.6 [2004-12-11]
This (public) command shows a list of all IRCOps that are only (except hidden ones), along with their level (netadmin, services admin, ..) and their away status.

CHANGES:
2004-12-11, v3.5: Now maintaining this module (originally coded by AngryWolf)
2005-03-07, v3.6: Fixed compiler warning with upcoming 3.2.3.

3.2 [2011-11-12]
Adds a /STAFF command that displays the contents of a file (or URL if remote includes are enabled).
CHANGES:
2004-12-11, v3.0: Now maintaining this module (originally coded by AngryWolf)
2004-12-12, v3.1: Bugfix, specified file was simply not working (huh ? ;p)
2011-11-12, v3.2: Make it compile on Unreal3.2.9

0.0.1 [2004-04-22] (will be in Unreal3.2.9+)
This module adds a new extended bantype ~E that can be used to exempt registered users from bans. For example:
+b *!*@*
+e ~E:Brian
+e ~E:John
Would ban everyone except the registered users Brian and John (that means: their nick needs to be Brian or John AND they should be umode +r).
Very simple concept/module, yet it can be quite useful ;).

CHANGES:
2004-04-22, 0.0.1: Public release


Have a look at my Products page to see (far) more advanced modules, and more information on custom coding.