What are the top tools to get the word out about your current vacancies ?

Social channels and networks spreads the word in seconds and as you mentioned its the most effective tool nowadays.
Postings on different networks gives company x exposure and what makes company x different from many other posts.
The way the recruiter post the vacancy or the AD and the Logo of the company/ company profile ..Etc

Using different social media networks had become an effective tool , so posting a vacancy in facebook,twitter,linked in,etc..
will for sure give exposure and prompote WOM

I have been using (لقد تم حذف الرابط بسبب انتهاكه لسياسة الموقع. يرجى التواصل مع قسم الدعم لمزيد من المعلومات.) for announcing the new opening and found it very effective, reason being;

1 - Quick penetration among the candidates.

2 - Cost effective.

3 - Promote company image among followers.

4- Attracts multiple profile.

Though I also send the announcement to internal employees and do effective networking which helps to generate resume. Additionally, i also approach the "Placement Cell" of reputable universities where we have fair idea about availability of potential candidates.

Using different social media