List of my favorite Firefox 3.5.x compatible extensions:


Extension Official Page
add_bookmark_here-3.5.20090621 Linux - Windows link
adblock_plus-1.1 link
bugmenot-2.1 link
codetch 0.4.3 link
copy_link_name-1.2.8 link
copy_plain_text-0.3.3-ff3.5 link
copyurlplus-v1.3.2 link
cutemenus_-_crystal_svg-1.9.3 link
dom_inspector-2.0.3 link
dictionarysearch-3.5.1 link
distrust-0.8.2 link
downthemall-1.1.4 link
extended_statusbar-1.5.4 link
firebug-1.4.0 link
flagfox-3.3.14 link
gmail_manager-0.5.7.2 link
google-notebook link
gtranslate-0.5.1 link
jsview-2.0.5 link
menu_editor-1.2.6 link
pencil-1.0.5 link
permit_cookies-0.6.2 link
printpdf-0.75 LIN - printpdf-0.75 WIN link
read_it_later-0.9947 link
regular_expressions_tester-1.1.6.13 link
right-click-link-1.1.3 link
tinyurl_2.0 link
titlebar_tweaks-1.8.0 link
too_many_tabs-0.4.4 link
user_agent_switcher-0.7.2 link
video_downloadhelper-4.6 link
web_developer-1.1.8 link
x-forwarded-for_spoofer-1.0.2b link