A frailichen lechtigen Chanukah! It is officially the last day of Chanukah, which is known as Zos Chanukah, particularly in chassidishe circles. There are many segulos discussed in regards to this holy day, including that it is the true day of the final sealing of the Divine verdicts from Hashem.
The B’Nei Yissoschor brings one particular segulah as part of learning that Rosh HaShanah and Chanukah are intrinsically related. That is the segulah of פקודת עקרים ועקרות, basically remembering the infertile and helping them to have children. This is only one of many, but one that seems to be of particular concern to those who worry about such things.
The biggest segulah though of Chanukah is tied with what B’nei Yissoschor brings in name of the Arizal in relation to the mitzva of lighting the menorah. Each night, during the first brocho particularly, we bring down a set of of the 13 Middos HaRachamim. On the last lighting, we complete this process, which means from the time the menorah is lit until after Chanukah is over, we have a wonderful es ratzon (time of will/acceptance of prayer) for asking for everything we need. This is an incredible time for doing t’shuva as well, since it is just like the Yomim Noraim before the gates are sealed. By many chassidim there is a minhag to wish “g’mar chasima tova,” just like between Rosh HaShanah and Yom Kippur because of this.
The most important thing to remember though is that through our rejoicing in Chanukah and serving Hashem through the mitzvos of this period of time, we can merit to attain a glimpse of the y’mos haMoshiach. As it is the eighth day, which is for a specific reason beyond the nes lasting so long (which is yet another proof as to the significance of “eight”), we have to consider the meanings of eight. Eight is the number of the day of bris milah, when a Jewish boy is initiated into the bris of Avraham Avinu; the number beyond the natural order, which generally goes til seven (such as the days of Creation, naturally observable planets etc); as well as the number of Moshiach, meaning that this is the number of wonders and things beyond nature. Through our tefillos and rejoicing today, we can accomplish things far beyond the normal running of the world, and bring the y’mos haMoshiach ever closer, in the day that what we say on Rosh HaShanah כי תעביר ממשלת זדון מן הארץ (for you shall eradicate the reign of the wicked from the world) will be fulfilled, may it come swiftly.