You mean other than Website? ;-)
I have had good luck with SWK, who after a little bit of a rocky start became one of the few third party vendors I found that I didn't have to babysit for a referral fee. There's no way to kill a referral relationship faster than to make consultants call to check on commissions. SWK sent it before I knew to even call. Scanforce has been the same way.
On the technical side, I didn't end up using them but quite a few years ago RedTail took a ton of time to visit a customer site once for EDI and they went above and beyond to make sure what they offered was a fit. What I liked here is that it felt like a consulting visit and not a sales pitch.
Other than that I pretty much refer everyone who is in the group and have had good experiences.