I love to alter drum machine sounds in many ways.
I send individual sounds through
an ART Pro VLA compressor, and I've also used
the Presonus Bluemax. It really fattens the sound and is great for times when you want it to stand out in a mix. You want to be careful not to destroy the attack transient, so experiment with the attack and release times. A lot of hip-hop and techno producers use compression in creative ways, such as causing "pumping" for an effect.
Tube preamps work great. Sending a snare drum through a guitar amp and miking it works great too. My favorite piece of gear is
my Sansamp PSA-1(amp simulator), for running drum sounds and keyboard sounds through it. Any amp modeler such as the Pod, J-station, and DG Stomp do the same thing. Distortion pedals can be fantastic for giving a sound a lo-fi vibe. Running cymbals through a flanger or phase shifter pedal is worth trying.
I like to just alter one or maybe two of the drum sounds, instead of the whole kit. If you just want a more punchy upfront sound, I recommend running some or all of the sounds through a tube preamp.