I was in the need to interface an Arduino board with 3v3 level logic (to use the great JTAGEnum !) so
I decided to build this simple level shifter shield.
It is based on TI's TXS0108 (8bit level shifter) which provides bidirectional level translation and
can accept 1.2 to 3.6 on one port (A) and 1.65 to 5.5 on the other port (B).
The shield has just one shifter wired to Arduino digital port:
The TXS0108 has a TSSOP package which has tiny spacing but can be soldered by hand (I used the usual method of soldering all pins and remove excess solder with desoldering wick).
If someone wants to build or enhance (like adding one more translator) i've provided the schematic and board files (in Eagle format).