These are my most used Drupal Modules:

token : provides token handling services
cck : Content Construction Kit
image
views
date : a flexible date/time field type for the cck
fckeditor - WYSIWYG HTML editor
wysiwyg : use client-side editors (a.k.a. WYSIWYG editors)
calendar
pathauto : generate path aliases
captcha
imagecache
webform
advanced_help
link : a CCK content field
site_map
admin_menu
imce : image/file uploader and browser
nodewords : Meta tags
google_analytics
filefield
imagefield : an image upload field for CCK
simplenews : Send newsletters to subscribed e-mail addresses.
jquery_update : an upgrade of jQuery
devel
acl: API for Access Control List
print : Printer, e-mail and PDF versions
ubercart : an e-commerce suite
forum_access
content_access : permissions for content types by role and author
diff
img_assist : upload and insert images inline into content
tinymce
buddylist : or buddylist2 for Drupal6
og : Organic groups
adsense
nice_menus
feedback : send feedback messages about the current displyed page
event
guestbook
panels
imageapi
blockbar : Outlook style block. not available for drupal6
taxonomy_theme
workflow_ng : customize the built in workflows in a very flexible way
xmlsitemap
CiviCRM
tapir : Tables API. Drupal 5 only
E-Commerce
counter : counts how many visitors on your website
taxonomy_menu
db_maintenance
Survey
Avatar Selection
ubrowser : the new way to browse taxonomy
freelinking : creating links to content
wikitools
languageicons : provides icons for language links
getid3 : extract information from MP3s and other multimedia file
signup
quote
auto_nodetitle
mollom : solution for all spam problems
talk : puts comments on a separate tab
i18n : Internationalization
Amazon associate tools
tableofcontents
quicktags : HTML tags for textarea
content_profile : user profiles as content
translation_overview
Import / Export API
html_to_text
blockcache
spam
geshifilter : syntax highlighting
comment_mover
Category
dhtml_menu
subscriptions
votingapi : Voting API
FeedButtons
cmf : Content Management Filter
globalredirect : Global Redirect
Forward
privatemsg
emfield : Embedded Media Field
extlink : differentiate between internal and external links
spamspan : SpamSpan filter
logging_alerts : Logging and alerts
views_cloud
imagepicker : Image Picker
swftools
privatemsg_rules : allow certain actions to send privatemsg
notifications : a complete Subscriptions/Notifications Framework
masquerade : switch users
lightbox2
viewfield : a CCK field module that allows put views into nodes.
menu_attributes
views_attach : “Profile” and “Node content”
tagtool : an enhance for tag input field
views_calc : adds simple calculations to a views table
taxonomy_multi_edit : Taxonomy Multi Editor
systeminfo : System information
weblinks
vitzo_easy_translator : makes I18N (Internationalization) easy
update_form_enhancement
transliteration
userplus
graphstat : graphs for statistics
poormanscron : cron
userprotect
update_advanced : Update status advanced settings
viewreference : a CCK field which allows include views into nodes
statistics_advanced : Statistics Advanced Settings
translation_status
linkchecker : Link checker
themekey : generic theme switching
http_request_fail_reset
phone : a phone field type for CCK
messaging : a Messaging Framework
scheduler : nodes to be published and unpublished on specified dates
private_upload : Upload files into a private directory
javascript_aggregator
role_delegation
services : provide web services via multiple interfaces
protect_critical_users : protects critical users from being deleted
taxonomy_access
sitedoc : Site Documentation
smtp : SMTP Authentication Support
search_engine_referers
search_and_replace
location
realname
module_filter : a new module layout
permission_select : quicker editing of role permissions
restrict_password_change
menu_breadcrumb : use the menu for the breadcrumb
tac_lite : Taxonomy Access Control Lite
special_menu_items
friendlist : relationships between users
advpoll : Advanced Poll
pathologic: an input filter
flashvideo
path_redirect
ffpc : FileField Podcaster
dashplayer : Dash Media Player
node_clone
moduleinfo
blocks404 : 404 Blocks
genpass : Generate password
audio
languageinterface : Consistent Language Interface
language_sections
encl_remote : attach a remote resource link to any node
jquerymenu : click and expand menus
browscap : a replacement for PHP’s get_browser() function
fancyzoom : image zoomer
core_translation : Core translation import
download_count
email : a CCK field type for email addresses
faq : Frequently Asked Questions
config_perms : adds more granular control for administer configuration
advuser : Advanced User
filterbynodetype : restrict the available input formats by node type
gallery : embeds Gallery2
recent_changes
css_gzip
computed_field : a very powerful CCK field
greybox : display web sites on top of your current page as a popup
comment_subject : fills in a default comment in the comment form
nodehierarchy : Node Hierarchy
filebrowser
front : Front Page
pathfilter
gravatar
firestats : a web statistics system
form_store : a list of forms
mail_edit
attachment: an alternative to Drupal’s upload module
mlm : Mailing List Manager
flashnode
filemanager : file management API
private : only be seen by the node author
node_images
simplenews_template
contemplate : Content Templates
bbcode
fivestar : voting
thickbox
update_status : drupal 6 do not need this module
webfm : File Manager
views_checkboxes
views_tabs : the presentation of views through tabs
views_savefilter
views_filterblock : Views Filter Block
simplemenu
prog_gallery : PROG AJAX based galleries
views_bonus : Views Bonus Pack
comment_notify : send notification e-mails about new comments
custom_pagers
assetfield
cck_address
notify : subscribe to periodic emails with new content and/or comments
pubcookie : authenticate using pubcookie
user_import
stringoverrides : String Overrides
smsemail
send : Adds “tell a friend” functionality to any node type
news : deliver one or more nodes to a mailing list
submenutree
referer_theme : different themes depending on the referer
gsitemap : Google Sitemap
mimemail
ad
node_expire
imagemenu
aggregation
imagecache_actions
backup_migrate
calendar_block
heartbeat : displays user activity
menuclass : add HTML classes to menu items
imagecache_profiles