Ages ago, I frequented Aerolite Gaming's DarkRP server that rotated between BMRP and HL2RP. In former I think I usually was a janitor, and latter I picked up prison guard OTA's role frequently even if I meant I was mostly stuck in Nexus and its prison cells - since proper OTA were a donator benefit. Also took part in CombineControl's original playtesting phase, got into Civil Protection via IC, in-game application. Though I don't remember much of the time I spent there since IIRC the community shut down soon enough, and somebody bought the CC scheme and domain, branding itself as the 'original' CombineControl community.
Besides that, I can't recall really visiting other HL2RP places. You know, besides LemonPunch being the most 'recent' old server I've been in.