Gigging without a decent amp can be a real pain sometimes but technology has allowed us to be able to overcome this problem. Direct-to-board rigs do pose some new challenges, though. Monitoring, sound leveling and overall EQing are a few of them.
I've been using amp sims for about 3-4 years now. I bring my own amp if I have someone who can help me, but these days I just go out with my pedalboard and pedal amps just in case I need to plug directly to the mixer. I had a Tech 21 Liverpool in the past and it saved my arse a lot of times. I then moved on to a Carl Martin Rock Bug DI/ampsim. It's not a fixture on my rig but I always have it in my gig bag. I also had an Ethos OD preamp before (I'm getting the new version pretty soon).
Monitoring is the biggest challenge for me. This is because if you're directly plugged to the mixer, your sound is at the mercy of the tech at the mixing booth. Sometimes the monitor would sound loud enough but my sound level would be near zero at the FoH. Sometimes it's the other way around. And sometimes my stage and FoH mix even sound different (i.e. when the on-stage monitor is a beat-up amp - this is usually the case in churches). I worked with the in-house techs and I made sure that we were on the same page as to how I should sound in the mix.
Any active gigger here who uses pedal amps, DIs and multi effects to directly connect to the PA/mixer? What's in your rig? How do you configure your sound to sound well with the PA/FoH when you're already onstage?