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

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

NEW: All modules now support both UnrealIRCd 3.2.x and UnrealIRCd 4. The installer will automatically compile & install the right version.

REMOVED: antimoon, antidccbug, bopmhelper, jointhrottle and regexcept. The functionality of these modules has either been added to core UnrealIRCd or they are no longer useful because they protect against threats that no longer exist.

1.4 [2015-10-17]
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 :).
0.1.1, 2005-01-06: Public release
1.0, 2005-06-21: Stable release, moved nearly all configurable parts to config, 10x speed up, and more..
1.1, 2005-07-21: Fixed an issue with digits and some other checks, this resulted in a too low score.
1.2, 2005-12-09: Added 'warn' action (warning only), added logging to ircd.log (if enabled).
1.3, 2011-11-09: Convert nick/ident/host to lowercase before doing random checks (convert-to-lowercase)
1.4, 2015-10-17: Support for UnrealIRCd 4

2.2 [2015-10-17]
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*

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
2.2, 2015-10-17: Support for UnrealIRCd 4

1.2 [2015-10-17]
This module will strip control codes (bold/underline/reverse) if the channel is +S, and block such messages if the channel is +c.
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.
1.2, 2015-10-17: Support for UnrealIRCd 4

1.2 [2015-10-17]
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.
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.
1.2, 2015-10-17: Support for UnrealIRCd 4. Module is now called 'privdeaf' and not 'm_privdeaf'

1.0 [2015-10-17]
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>
/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).

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)
1.0, 2015-10-17: Support for UnrealIRCd 4. Module is now called 'jumpserver' and not 'm_jumpserver'

3.71 [2015-11-28]
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.

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.
2015-10-17, v3.7: Support for UnrealIRCd 4
2015-11-28, v3.71: Fix bug with UnrealIRCd 4: didn't list remote ircops

3.8 [2015-10-17]
Adds a /STAFF command that displays the contents of a file (or URL if remote includes are enabled).
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
2015-10-17, v3.8: Support for UnrealIRCd 4

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