You might not have considered an amp stand before, but it can make a big difference. This offering from IsoAcoustics has three main benefits: it tilts your amp back (aiming the sound at your ears, rather than your feet), raises it off the floor, and isolates it from other surfaces.
The stand is surprisingly sturdy - we wouldn't put a 4x12 on there, but for combos, it's ideal. Sound-wise, it imbued our Vox AC15 with less low-end flub and a clearer midrange.
There are cheaper stands, but the IsoAcoustics' effects are worth experiencing.