My field research is decidedly low-tech (see Transect Ropes Redux). You really don't need much stuff to lay out an inventory transect: 1) a transect rope with knots to correct for slope (yellow nylon), 2) a Silva ranger compass to keep you going straight, 3) a Speigel Relaskop for measuring slopes and heights (in leather case), and 4) Forestry Suppliers fieldbook for recording the data (I use their orange, hardback, six column Level book, No. 5737).
[NOTE: Image is from the 2005 rattan survey in the Hukaung Valley, Myanmar (see Hukaung Valley Rattan Survey). With the exception of the transect rope, I still have - and use - all of these tools].