Post-processing with Tecplot
Starting with OF-1.6., OpenFOAM includes the utility foamToTecplot360 to facilitate post-processing using Tecplot 360 (2009 and newer). The most recent versions of Tecplot (2011-R2 and up) can natively open OpenFOAM files as long as the mesh is stored in ASCII format.
To convert OpenFOAM data to tecplot, run the foamToTecplot360 utility. This will create a subdirectory "Tecplot360", in which a .plt file will be created for every time step, plus an additional caseName_grid_0.plt file that contains the mesh information. Start Tecplot, and then execute "File->Load Data File(s)". Select "Tecplot data loader" as the data format and continue to the file selection dialogue. Click the command button "Multiple Files". Do this even if you just want to load a single time step, because you'll need both the data and the grid file.
Now, make sure the first file you add to the list of files to load is the previously mentioned mesh file (caseName_grid_0.plt), then add the rest of the files you wish to view (as usual selection of multiple files can be done using Shift/Ctrl + Click) and hit "OK".