Well if you use OSX or any program that produces metadata files on your file-system, it can become a nightmare trying to sort through the files you need to check in to svn... However! Once you discover there is a little hidden global ignore feature in svn, all the horror goes away.
On OSX the file of concern is located :
Linux (sometimes) :
Windows... No idea sorry, depends on your client, though apparently TortoiseSVN has it as an option...
To add a file or folder to the list just open up that file and find the "global-ignores" option. It's just a space separated list of potential file or folder names that you want to ignore.
Mine now looks like this:
global-ignores = *.o *.lo *.la *.al .libs *.so *.so.[0-9]* *.a *.pyc *.pyo _notes .DS_Store .#* .AppleDouble *:2e_* ._*
Have fun with a cleaner svn...
More information on the config options:
Subversion Manual: Config