You’re probably safest excluding particular filetypes, rather than picking those you want to include, as you could then add a new type and not realize it wasn’t versioned.
On a per-directory basis, you can edit the svn:ignore property.
Run
svn propedit svn:ignore .
for each relevant directory to bring up an editor with a list of patterns to ignore.
Then put a pattern on each line corresponding to the filetype you’d like to ignore:
*.user
*.exe
*.dll
and what have you.
Alternatively, as has been suggested, you can add those patterns to the global-ignores property in your ~/.subversion/config file (or "%APPDATA%\Subversion\config" on Windows – see Configuration Area Layout in the red bean book for more information). In that case, separate the patterns with spaces. Here’s mine. # at the beginning of the line introduces a comment. I’ve ignored Ankh .Load files and all *.resharper.user files:
### Set global-ignores to a set of whitespace-delimited globs
### which Subversion will ignore in its 'status' output, and
### while importing or adding files and directories.
# global-ignores = *.o *.lo *.la #*# .*.rej *.rej .*~ *~ .#* .DS_Store
global-ignores = Ankh.Load *.resharper.user