This is the page for my – and others' – userboxes that gets transcluded on my userpage. If you want to use one that I've made, open the source code, copy the template name, and put it wherever you'd like. Here are some links for them if you don't feel like doing that though.

Wikitext userbox where used
{{User:theki/ubx/Syro}}
This user loves Syro by Aphex Twin.
linked pages
{{User:theki/ubx/22, A Million}} linked pages
{{User:theki/ubx/Wikisourcer for|day=31|month=12|year=2005}}
This user has been on Wikisource for 18 years, 10 months and 3 days.
linked pages

Userboxes
??This user hasn't revealed what gender or race he/she/it/they are. Nor what species, for that matter.
This user has been on Wikipedia for 7 years, 4 months, and 19 days.
This user has been on Wikisource for 4 years and 15 days.
æthis user is an autechre fan
IDMThis user enjoys braindance.
This user loves alternative rock.
This user loves Syro by Aphex Twin.

enThis user is a native speaker of the English language.
es-0Este usuario no entiende español (o lo entiende muy difícilmente).
HTML-5This user is a professional HTML user.
js-5This user is a professional JavaScript programmer.
C#-3This user is an advanced C# programmer.
Lua-4This user is an expert Lua programmer.
Java-3This user is an advanced Java programmer.
This user is an advanced Go programmer.