Grep and recursion

Grep has for a long time had a recursive option "-r" but I have never been able to get it to do what I want because if you write

$ grep -r test *.txt

The *.txt part specifies the files to look in, and since the folders I want to recurse don't end with .txt it doesn't recurse into them.
The correct way to cause grep to recurse is to specify file patterns separately.

$ grep -r test --include "*.txt" ./

Using -exec instead of xargs

Using xargs to pipe results of find into grep has problems if find returns files/folders with spaces in the name.

find ./ -name "*html" | xargs grep "something"


Ends up giving me lots of "file doesn't exist" errors.

Using exec circumvents this problem, although using exec is apparently a less efficient way of doing things.

find ./ -name "*html" -exec grep -H "something" "{}" \;

-H tells grep to always show the filename, otherwise you only get the match.
"{}" represents the filename returned by find.
\; I'm not sure what this is, but it has to be there...

Update:
I describe a slightly simpler solution in this posting.